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Question: 1
Define Relative atomic mass?
Answer: 1
1-861"Relative atomic mass of an element is the average masses of atoms of that element as compound to 1/12th the mass of one atom of Carbon-12 isotope.
Example: Mass of Na = 23 amu
When atomic mass unit is expressed in grams, it is.
1 amu = 1.60x10-24 g
Question: 2
What is the application of Inorganic Chemistry?
Answer: 2
2-861It has application in every aspect of chemical industry such as glass, cement, ceramics and metallurgy.
Question: 3
Name one solid, one liquid and one gaseous element present at room temperature?
Answer: 3
3-861Solid : Sodium, Iron
Liquid: Bromine and Mercury
Gas: Oxygen , Nitrogen, and Chlorine
Question: 4
Define Industrial Chemistry and Analytical Chemistry.
Answer: 4
4-861Industrial Chemistry:
"This branch of chemistry is related to the the industrial processes" It is associated with studies of properties uses and application of techniques for the preparation of industrial sales on large scale.
Question: 5
How can you justify that air is a homogeneous mixture. Identify substances present in it?
Answer: 5
5-861Air is a mixture formed by be the physical mixture of the substances like nitrogen, oxygen, carbon dioxide, noble gases and moisture and it has same composition throughout. So,it is homogenous mixture.
Question: 6
Define Empirical formula and give examples.
Answer: 6
6-861"It is the simplest whole number ratio of atoms present in a compound"
Example:
Empirical formula of benzene(C6H6) is CH
Empirical formula of Hydrogen peroxide (H2O2) is HO
Question: 7
What are the uses of Nuclear Chemistry?
Answer: 7
7-861It has vast application in medical treatment, preservation of food and generation of electrical power through nuclear reactors.
Question: 8
What is the significance of the symbol of an elements?
Answer: 8
8-861Significance of the symbol of an element:
Symbols are used for elements instead of writing of their complete names. So, it takes less time save time and element can be recognized by that symbol in all over the world. For example
oxygen,sulphur, Nitrogen
Question: 9
On the basis of properties, elements are divided into which groups?
Answer: 9
9-861On the basis of properties elements are divided into metals, non-metal, and metalloids
Question: 10
Define Chemistry?
Answer: 10
10-861The Branches of Science which deals with the composition, structure, properties and reactions of matter is called chemistry.
Question: 11
Give the composition of Earth Crust with respect to three major elements.
Answer: 11
11-861Earth Crust is formed by three major elements having following percentages.
Oxygen 47%
Silicon 28%
Aluminum 7.8%
Question: 12
Is atomic mass unit a SI unit of an atomic mass?
Answer: 12
12-861Yes , Atomic mass unit is SI unit of atomic mass.
Question: 13
Define atomic mass unit. Why is it needed?
Answer: 13
13-861Atomic Mass Unit: The unit for relative atomic masses is called atomic mass unit.
Symbol:Its symbol is amu.
One atomic mass unit is 1/12th the mass of one atom of carbon -12th the mass of one atom of carbon-12th . When this atomic mass unit is expressed in grams, it is : 1 amu=1.66 x 10-24 g
Question: 14
What is the relationship between atomic number and atomic mass?
Answer: 14
14-861The relationship between atomic number and atomic mass is as following.
A = Z = n
Where A = mass number
Z = Atomic number
n= no of neutrons
Question: 15
Find out the mass of 3 moles of oxygen atoms.
Answer: 15
15-8613 x 16 = 48 g of oxygen are present in 3 moles.
Question: 16
What is atomic number, how it is represented?
Answer: 16
16-861"The atomic number of an element is equal to the number of protons present in the nucleus of its atoms."
Representation:It is represented by "Z"
Question: 17
What is teh relationship between mass and mole of a substance?
Answer: 17
17-861The relationship between mass and mole of substance is given as following mass of substance = No of moles x Molar mass of substance
Question: 18
What do you mean by 1 atom carbon and 1 gram atom of Carbon.
Answer: 18
18-861One atom of carbon has its atomic mass which is 12 amu . But when this mass of carbon atom is expressed in gram then it is known as gram atomic mass. As 1 gram of carbon =12.0 g.
Question: 19
is the mass of 1 mole of Oxygen and 1 mole of Sulphur same.
Answer: 19
19-861No, the mass of 1 mole of oxygen and 1 mole of sulphur atom is not same.
Question: 20
Define empirical formula and give examples.
Answer: 20
20-861It is the simplest whole number , ratio of atoms present in a compound."
Empirical formula of benzene
Empirical formula of Hydrogen peroxide
Question: 21
Why atomic mass of an atom is defined as relative atomic mass?
Answer: 21
21-861ATomic mass of an atom is defined as relative atomic mass, because atomic mass of an atom is the mass which compares or relates with 1/12th mass of carbon 12 isotope.
Question: 22
What are application of inorganic chemistry.
Answer: 22
22-861It has application is every aspect of chemical industry such as glass, cement, ceramics and metallurgy.
Question: 23
What is valency?
Answer: 23
23-861The combining capacity of an element with other elements is called valency
For example. Valency of carbon is 4
Question: 24
How many atoms are present in one gram atomic mass of a substance?
Answer: 24
24-861One gram atomic mass of a substance is equal to Avogadro's number in which 6.023 x 1023 atoms are present
Question: 25
How many atoms are present in 16 g of O and 8g of S?
Answer: 25
25-86116 grams of oxygen has 6.022 x 1023atoms and 8 grams of sulphur has 1.055x1023atoms.
Question: 26
Which term is used to represent the mass of 1 mole of molecules of a substance?
Answer: 26
26-861Gram molecular mass
Question: 27
Write difference between physical and chemical properties .
Answer: 27
27-861Chemical properties :
1: It depends upon the composition of the substance
2: When a substance undergoes a chemical change , its composition change and a new substance is formed .
Example : When hydrogen react with oxygen , it form water , chemical change
Question: 28
How many atoms are in I amu and I g of hydrogen .
Answer: 28
28-8611 amu and 1 gram of hydrogen has 6.022x1023 atoms.
Question: 29
Define Biochemistry.
Answer: 29
29-861"It is branch of chemistry in which we study the structure, composition and chemical reactions of substances found in living organisms .
Question: 30
How many times is 1 mole of oxygen atom heavier than 1 mole of hydrogen atom?
Answer: 30
30-861One mole of oxygen atom is 16 times heavier than the one mole of hydrogen.
Question: 31
What is Radical?
Answer: 31
31-861An atom or a group of atoms that have some charge and keeps in contact during a chemical reaction is called a radical e.g. Hydronium and carbonate.
Question: 32
Define organic chemistry and which industries covered by it
Answer: 32
32-861Organic chemistry : it is the study of covalent compounds of carbon and hydrogen and its derivatives
Question: 33
Write down the name of any two elements which were discovered in early ages .
Answer: 33
33-861Following elements were discovered in early ages
Question: 34
What is meant by variable valency?
Answer: 34
34-861Some elements show more than one combining power that is called variable valency for example, in Ferrous sulphate the valency of Iron is 2 whereas in ferric sulphate the valency of iron is 3
Question: 35
What is free radical? Give example.
Answer: 35
35-861"Free radicals are atoms or group of atoms possessing odd number of electrons".
Example: It is represented by putting a dot over teh symbol of an element e.g. H+,Cl-,H3C, Free radical are generated by teh homolytic breakage of the bond between 3 two atoms when the absorb heat or light energy A free radical is extremely reactive species as it has the tendencyto complete its octel.
Question: 36
What is difference between elements and compound ?
Answer: 36
36-861Compound : Compound is a substance made up of two or more elements chemically combined together in a fixed ratio by mass
Example : Water (H2O)
Question: 37
In which branch of chemistry behaviour of gases and liquid is studied?
Answer: 37
37-861The behaviour of gases and liquids is studied in the branch of chemistry called physical chemistry.
Question: 38
Define matter and mixture .
Answer: 38
38-861Matter : anything that has mass and occupies space is called matter . Matter exists in three physical states , solid , liquid , gas
Question: 39
If 16 gram of oxygen contains 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams.
Answer: 39
39-86116 g of oxygen = 1 mole of oxygen
Mass of one atom of oxygen = 16 grams.
Question: 40
Which branch of chemistry deals with preparation of paints and papers?
Answer: 40
40-861"Industrial chemistry deals with preparation of paints and papers."
Question: 41
Define chemistry ? Explain two branches of chemistry .
Answer: 41
41-861Chemistry : The Branch of science which deals with the composition , structure, properties and reaction of matter is called chemistry
Question: 42
In which branch of chemistry deals with preparation of paints and papers?
Answer: 42
42-861"Industrial chemistry deals with preparation of paints and papers".
Question: 43
Which branch of chemistry deals with energy of atoms and its uses in daily life.
Answer: 43
43-861Nuclear chemistry deals with energy of atoms and its uses in daily life.
Question: 44
What is the valency id following ?
(A) Barium (B) Nitrogen (C) Sodium (D) Sulphur
Answer: 44
44-861Elements valency
1: Barium 2
2: Nitrogen 3
3: Sodium 1
4: Sulphur 2
Question: 45
What is radical
Answer: 45
45-861An atom or a group of atoms that have some charge and keeps in contact during a chemical reaction is called a radical e.g. Hydronium H2O and carbonate CO3-2
Question: 46
What is the relationship between empirical formula and formula unit.
Answer: 46
46-861All the organic compounds are represented by formula unit. Formula unit is also and empirical formula of Ionic compounds.
Question: 47
What is relative atomic mass ? How is it related to gram ?
Answer: 47
47-861The relative atomic mass of an element is the average mass of an atoms of that element as compared to 1/ 12th the mass of an atom of carbon -12 isotope . Atomic mass unit is represent by amu and in grams 1amu =1.66*10-24g
Question: 48
What is meant by mixture ? Give example.
Answer: 48
48-861When two or more elements or compounds mix up physically without any fixed ratio they form a mixture
Question: 49
Write any two applications of inorganic chemistry.
Answer: 49
49-861Inorganic chemistry has applications in following aspects of the chemistry industry
Question: 50
Give some examples of arsenic and silver .
Answer: 50
50-861Symbols of arsenic and silver are as following
Question: 51
Give the composition of milk.
Answer: 51
51-861Milk is a mixture of calcium , water, sugar, fat, proteins, minerals, salts and vitamins.
Question: 52
Define industrial chemistry and analytical chemistry ?
Answer: 52
52-861Industrial chemistry : It is the branch of chemistry that deals with the manufacturing of chemical compounds on commercial scale
Question: 53
For an element Z = 92 A = 238 Calculate number of neutron in it
Answer: 53
53-861Atomic mass = No of protons + No of neutrons =A=238
No of protons Z = 92
No of neutrons =N=A-z
=238-92= 146
Question: 54
Which branch of chemistry deals with the structure and properties of naturally occurring molecules.
Answer: 54
54-861"Organic chemistry deals with the structure and properties of naturally occuriring molecules."
Question: 55
Differentiate between empirical and molecular formula.
Answer: 55
55-861Empirical formula: it is the simplest whole number ratio of atoms present in a compound
e.g. Empirical formula of benzene is CH.
Question: 56
Write down chemical formula of calcium phosphate and sodium chloride ..
Answer: 56
56-861Chemical formula of calcium phosphate and sodium chloride is as fellows :
Question: 57
Differentiate between nuclear chemistry and environmental chemistry .
Answer: 57
57-861Environmental chemistry:
1 :The branch of chemistry in which we study about components of the environment and effect of human activity on the environment
2 :it is also concerned with other sciences like biology, geology
3: Save environment from pollution
Question: 58
What is the relationshp between atomic number and atomic mass?
Answer: 58
58-861The relation between atomic number and atomic mass is as following A = Z + n
Question: 59
What is meant by element ? Explain with example .
Answer: 59
59-861Element is a substance which is made up of some types of atom , having same atomic number and it cannot be dissolved into simple substances by ordinary chemical means
Question: 60
Define relative atomic mass.
Answer: 60
60-861Relative atomic mass of an element is the average mass of an atom of that element as compared to 1/12th the mass of atom of carbon-12 isotopes
Question: 61
Write name of any two elements found in gaseous state
Answer: 61
61-861Nitrogen and oxygen both found in gaseous state
Question: 62
Explain difference between physical chemistry and biochemistry .
Answer: 62
62-861Physical chemistry: physical chemistry IS defined as the branch of chemistry that deals with the relationship between the composition and physical properties of matter , along with changes in them
Question: 63
Write two significance of chemical formula .
Answer: 63
63-8611: it indicates the mass of the compound in amu or grams
Question: 64
Write any two elements found in the liquid state at room temperature .
Answer: 64
64-861Mercury and bromine are two elements found in the liquid state at room temperature
Question: 65
Define Biochemistry ? Describe scope of biochemistry and give two examples of biochemistry.
Answer: 65
65-861The branch of science concerned with the chemical and physico-chemical processes and substances that occur within living organisms.
Question: 66
Write four examples of mixture .
Answer: 66
66-8611: Air is a mixture of nitrogen , carbon dioxide , noble gasses and water vapours
Question: 67
What is difference between cation and anion ?
Answer: 67
67-861Cation: An atom or group of atoms having positive charge on it is called cation
Example : like Na , k
Question: 68
Human body made up of how many elements ? Write their names .
Answer: 68
68-861Six elements constitute about 99% of our body mass , oxygen 65% , Carbon 18% , Hydrogen 10% , Nitrogen 3%, Calcium 1.5% and phosphorous 1.5% , Potassium , Sulphur , Magnesium and sodium constitute 0.8 % of our body mass . Wherease copper , zinc , chlorine , fluorine , iron , cobalt and magnesium constitute only 0.2% of our body mass
Question: 69
Define symbol and valency with example .
Answer: 69
69-861Symbol : The representation of any element with one or two english letters is called symbol.
Question: 70
Write chemical formula of Aluminium sulphate and Calcium phosphate .
Answer: 70
70-861Aluminium sulphate: Al2(SO4)
Question: 71
Name the elements represented by the following symbols W, Ba , Hg and Na
Answer: 71
71-861Tungsten W , Barium B , Mercury Hg , Sodium Na
Question: 72
What is difference between compound and mixture / Give example .
Answer: 72
72-861Compound :
1:It is formed by chemical combination of atoms of element
2:Its components lose their own properties and produce new substance that have entirely different properties
Question: 73
Write the percentage of volume by weight of oxygen in atmosphere and oceans
Answer: 73
73-861In atmosphere oxygen is 21% while in oceans it is 86%
Question: 74
Difference between homogeneous and heterogeneous mixture.
Answer: 74
74-861Homogeneous mixture: Mixtures that have uniform composition throughout are called homogeneous mixtures.
example: Milm, Brass, Ice-cream.
Question: 75
Differentiate between molecular mass and formula mass .
Answer: 75
75-861Formula mass:
1:The sum of atomic masses of all the atoms present in one formula unit of a substance is called formula mass
2:Formula mass is related to ionic compound
Examples : NaCl = 23+36.5= 58.5 amu
Question: 76
Soft drink is a mixture while water is compound . Give the reason .
Answer: 76
76-861Water : Water forms by the chemical reaction of hydrogen and oxygen . that's why it is called compound
Question: 77
Write the chemical formula of water and sugar.
Answer: 77
77-861Water :C12H22O11
Question: 78
Write down the chemical formulas of the following
(a) Sugar (b) Sulphuric acid
Answer: 78
78-861(a) Sugar : C12H22O11
Question: 79
If 16g of oxygen contains 1 mole of oxygen atom, calculate the mass of one atom of oxygen in grams .
Answer: 79
79-861No of atoms in one mole =6.02×1023
Question: 80
Differntiate between biochemistry and industrial chemistry .
Answer: 80
80-861Biochemistry : Biochemistry is the branch of chemistry in which w study the structure , composition , and chemical reaction of substances found in living organisms
Question: 81
Define atomic number and atomic mass .
Answer: 81
81-861Atomic mass :
1: The sum of number of protons and neutrons present in the nucleus of an atom is called atomic mass
2: It is represented by A
Example : Atomic mass of carbon is 12
Question: 82
What is meant by ion ? Give example .
Answer: 82
82-861Ion is an atom or group of atoms having a charge on it .
Question: 83
How does homogeneousmixture differ from heterogeneous mixture?
Answer: 83
83-861The mixture that has uniform composition throughout is called homogeneous mixture which composition is not uniform throughout e.g. soil , rock and wood etc.
Question: 84
What is the significance of the symbol of an element ?
Answer: 84
84-861Symbol means identification , in chemistry it is used for the representation of chemical name of an element . In chemical equation whole name of an element is difficult to write , because the formula or chemical equation becomes too lengthy . Thus symbol makes an easy representation and understanding in this case
Question: 85
Define atomic mass unit .
Answer: 85
85-861One atomic mass unit is 1/12th of the ,ass of one atom of carbon 12 . When this atomic mass unit is expressed in gram , it is 1amu = 1.66*10-24 g
Question: 86
Define chemical formula and give one examples .
Answer: 86
86-861Definition : A chemical formula is the symbolic representation the elements in the compounds and the ratio of the elements to one another
Question: 87
Write chemical reaction of H2 with F2 and Cl2 .
Answer: 87
87-861Reaction of H2 with F2: Flourine combines with hydrogen even in the dark and cold state
H2 +F2➜ 2HF
Question: 88
Define homogenous mixture and give example .
Answer: 88
88-861Homogenous mixture: The mixture having uniform composition is calledhomogenous mixture
Question: 89
What is meant by molecular ion ?
Answer: 89
89-861When a molecule loses or gains one or more electron , it forms a molecular ion
Question: 90
Define empirical formula and give an examples .
Answer: 90
90-861Empirical formula: empirical formula is a formula which represents the simplest whole number ratio of atoms present in a compound
Question: 91
Calculate the formulas mass of potassium sulphate
Answer: 91
91-861Formulas mass of potassium sulphate (K2SO4)
K2SO4 = 2(39)+(32)+4(16)
= 78+32+64
= 174a.m.u
Question: 92
Write two difference between atom and anion
Answer: 92
92-861Ion :
1: It is the simplest unit of ionic compound
2: It has net charge either negative or positive on it
Question: 93
Write short note on discovery of Neutron.
Answer: 93
93-861Chadwick discovered Neutrons in 1932 . He bombarded alpha particles on Beryllium . He observed that the radiation of very high penetrating power were produced ( They can move through long distance in air ) .These radiations were called Neutron
Question: 94
An element with A = 39 , Z = 19 .Calculate the number of electrons and protons in one atom of this element
Answer: 94
94-861Atomic mass of an element = A = 39
Atomic number of element = Z = 19
As we know that atomic number is the number of protons present in the nucleus of an atom so , proton and electron always equal in any atom , that's why ,
Number of protons =19
Number of electrons = 19
Question: 95
Define avagadro's number
Answer: 95
95-861Avagadro's number is a collection of6.02 × 1023 particles. It is represented by symbol 'NA'. Hence the6.02 × 1023 number of atoms , molecules or formula unit is called avagadro's number that is equal to 1 mole of respective substance
Question: 96
Define molecular mass and give example .
Answer: 96
96-861Molecular formula that shows actual number of atoms of each element present in molecules of that compound
Question: 97
Which gasses are present in air ? Write their names .
Answer: 97
97-861Oxygen , nitrogen , carbon dioxide , argon are major gasses present in air
Question: 98
Calculate molecular mass of NH3.
Answer: 98
98-861Molecular mass :
NH3 =14+1*3
=17a.m.u
Question: 99
State the nature and name of the substance formed by combining the following
1: Zinc + Copper
2: Water +Sugar
3: Aluminum +Sulphur
4: Iron + Chromium + Nickle
Answer: 99
99-8612: Water + Sugar
It will be a solution or mixture called sugar syrup
Question: 100
What is relationship between Empirical formula and Molecular formula ?
Answer: 100
100-861The relationship between Empirical formula and Molecular formulais given as
Molecular formula = (Empirical formula)*n
When n = 1,2 ,3 and so on
Question: 101
Write two / four characteristics of cathode rays.
Answer: 101
101-8611: Cathode rays travel perpendicular to the cathode surface
Question: 102
Write chemical formula of caustic soda and washing soda .
Answer: 102
102-861Caustic soda: NaOH
Question: 103
An element has 5 electrons in M shell . Find its atomic number
Answer: 103
103-861The element has 5 electrons in M shell has atomic number 15 and name of element is phosphorous
Question: 104
Calculate the number of mole carbon in 84 gram of carbon .
Answer: 104
104-861 Mass of C = 84 gm
Molecular mass of C = 12 gm
Quantity of moles = 84/12
= 7 moles
Question: 105
State three reasons why do you thing soft drink is a mixture and water is a compound .
Answer: 105
105-861Soft drink is a mixture because :
1: Its components are not bounded chemically
2: The components do not have fix ratio
Question: 106
Calculate molecular mass of sulphuric acid .
Answer: 106
106-861Molecular mass of sulphuric acid H2SO4
=2(1)+(32)+4(16)
=98amu
Question: 107
Give the composition of earth crust with respect to three major elements .
Answer: 107
107-861Earth crust is formed by three major elements having following percentages
Question: 108
Write two difference between molecule and molecular ions .
Answer: 108
108-861Molecule :
1: molecule is formed by the combination of two or more atoms . Which can exist independently and shows all the properties of that compound i.e CO2, CH4 etc
2: It is always neutral
3: It is formed by the combination of atoms
4: It is stable unit
Question: 109
Define m0ole and give example .
Answer: 109
109-861Atomic mass , molecular mass or formula mass of a substance expressed in grams is called a mole
Question: 110
What is meant quantum ?
Answer: 110
110-861Quantum means fixed energy . It is the smallest amount of energy that can be emitted or absorbed as electromagnetic radiation . Quanta is plural of quantum . In 1918 , Noble prize in physics was awarded to German physicist Max Planck ( 1858-1947) for work on the quantum theory
Question: 111
Write down the chemical formula of silicon dioxide and calcium chloride .
Answer: 111
111-861Silicon dioxide SiO2
Question: 112
Calculate the molecular mass of the carbon dioxide .
Answer: 112
112-861Molecular mass of the carbon dioxide
CO2 = 12+2 (16)
= 44amu
Question: 113
What is the empirical formula of acetic acid ? Calculate its molecular mass.
Answer: 113
113-861Empirical formula of acetic acid CH2O
Question: 114
Write electronic configuration of Aluminuim .
Answer: 114
114-861Atomic number of Aluminium is 13
13Al = 1s2 , 2s2, 2p6, 3s2, 3p1
Question: 115
Calculate no of carbon atoms in one mole C6 H12 O6
Answer: 115
115-8616 atoms of carbon are present in one mole of glucose
Question: 116
How free radical is formed ?
Answer: 116
116-861Free radicals are formed by the homolytic (equal) breakage of bond between two atoms when they absorb heat or light energy
Question: 117
What is mean by cation and anion? Explain with example.
Answer: 117
117-861Cation: Na ______> Na+ + 1e-
The cations are formed when an atom loses electrons from its outmost shells. For example cations are Na + , K+, Ca+ 2
Question: 118
What are applications of inorganic chemistry?
Answer: 118
118-861It has application in every aspect of chemical industry such as glass , cement , ceramics and metallurgy
Question: 119
Calculate the formula mass of the sodium sulphate .
Answer: 119
119-861Formula mass of the sodium sulphate :
Na2so4 =2(23) +(32)+4(16)
=46+32+64
=142amu
Question: 120
Ionic compounds are solids. Explain
Answer: 120
120-861Ionic compounds are made up of positively and negatively charged ions . Thus they consists of ions and not molecules . These positively charges ions are held together in a solid or crystal form
Question: 121
What would be the number of moles in 9.0 gram carbon ?
Answer: 121
121-861Number of moles of carbon = 9 g
Molar mass of carbon = 12 g
Number of moles = ?
Question: 122
Write down the chemical reactions of chlorine with hot and cold aqueous solutions of sodium hydroxides
Answer: 122
122-861Chlorine reacts with cold dilute NaOH to give sodium hypochlorite .
2NaOH +Cl2➜ NaCl+ NaOCL +H2O
Question: 123
Difference between molecular mass and formula mass.
Answer: 123
123-861Molecular Mass:
The sum of the atomic mass of all the elements present in a molecule is called as Molecular Mass.
Question: 124
What is difference between ion and free radical ?
Answer: 124
124-861Free radicals :
1: These are the atoms that have odd number of electrons . They do not have any charge
2: They can exists in solutions as well as in air
3: They may form in the presence of light
Question: 125
Write electronic configuration of chlorine and carbon
Answer: 125
125-861Electronic configuration of carbon : 12 C 6 = 1s2 , 2s2 , 2p2
Question: 126
What id meant by atom and ion?
Answer: 126
126-861Atom
1- It is the smallest particle of an smallest particle of an element.
2- It is electricallyneutral
3- It can take part in a chemical reaction
Question: 127
Define Triatomic molecule and polyatomic molecule
Answer: 127
127-861Polyatomic molecule : The molecules which consists of many atoms calledpolyatomic molecule
Question: 128
What is diffusion ? Explain with example .
Answer: 128
128-861Diffusion : The process in which molecules more from the area of higher concentration move to the area of lower concentration until the state of equilibrium is achieved is called diffusion
Question: 129
Calculate the gram molecule in 40g of phosphoric acid
Answer: 129
129-861Molar mass of phosphoric acid H3PO4 = 3+31+64=98
Question: 130
Define industrial chemistry and analytical chemistry
Answer: 130
130-861Industrial chemistry : This branch of chemistry is related to the industrial process . It is associated with studies of properties uses and application of techniques for the preparation of industrial sales on large scale
Question: 131
Difference between true solution and colloid solution?
Answer: 131
131-861True solution:Solutions are the homogeneous mixture of two or more than two components.
Question: 132
Write difference between homoatomic and heteroatomic molecules ?
Answer: 132
132-861Heteroatomic molecules:
The molecules consisting of different types of atoms are called heteroatomic molecules
Question: 133
How can you differentiate between organic and inorganic chemistry .
Answer: 133
133-861Organic chemistry : It is the study of the properties and behavior of hydrocarbons (compounds of carbon and hydrogen ) and their derivatives
Question: 134
Define element?
Answer: 134
134-861Sodium (Na) and Hydrogen (H) etc
Question: 135
What is matter ?
Answer: 135
135-861Anything which has mass and occupy space is called matter
Question: 136
Describe two characteristics of canal rays .
Answer: 136
136-8611: Canal rays travel in straight line in direction opposite to the cathode rays and cast a sharp shadow of an opaque object if placed in their path
Question: 137
Define formula mass and formula unit .
Answer: 137
137-861Formula unit : formula unit is defined as the simplest whole number ratio of ions ,as present in the ionic compounds
Question: 138
Give the scope of biochemistry .
Answer: 138
138-861It is the branch of chemistry in which we study the structure , composition and chemical reaction of substances found in living organisms . It covers all chemical processes taking place in living organisms . Such as synthesis and metabolism of bio molecules like carbohydrates , proteins and fat . Biochemistry emerged as separate discipline when scientists began to study how living things obtain energy from food or how the fundamental biological changes occur during a disease . Examples of applications of biochemistry are in the fields of medicine , food science and agriculture etc
Question: 139
Write the relation between empirical formula and molecular formula
Answer: 139
139-861There is a relationship betweenempirical formula and molecularformula which is given as:
Molecular formula= (empirical formula
Where n= 1, 2, 3,,,,,,
Question: 140
Calculate the formula mass of the nitric acid .
Answer: 140
140-861HNO3 = 1+14+48
= 63amu
Question: 141
Define ionic bond and ionic compounds .
Answer: 141
141-861Ionic bond : The type of chemical bond which is formed due to complete transfer of electron from one another is called ionic bond
Question: 142
What is meant by relative molecular mass?
Answer: 142
142-861Relative molecular mass:
The ratio of the average mass of one molecule of an element or compound to one twelfth of the mass of an atom of carbon- 12
Question: 143
Write properties of Neutrons .
Answer: 143
143-861Properties of neutrons particles are given below :
Question: 144
State John Dalton's atomic theory .
Answer: 144
144-861Main points of John Dalton's atomic theory are given as follows
Question: 145
Define atomic mass unit . Why is it needed ?
Answer: 145
145-861The unit for relative , atomic mass unit
Question: 146
How cation and anion is formed ?
Answer: 146
146-861Cation is formed by the loss of one or more electrons
Question: 147
Which are physical properties of matter ?
Answer: 147
147-8611: Matter exists in three physical state i-e gas, liquid , and solid
Question: 148
Define diatomic molecule and give example .
Answer: 148
148-861If a molecule consists of two atoms called diatomic molecule
Question: 149
How does electron differ from a neutron ?
Answer: 149
149-861Electron
1: Electrons have negative charge
2: The mass of the electron is 1940 times less than proton
Question: 150
Differentiate between gram atomic mass and gram molecular mass .
Answer: 150
150-861Gram atomic mass: The atomic mass of an element expressed in grams . It is called gram atomic mass
Question: 151
State the nature and name of the substance formed by combining the following
1: Zinc + Copper
2: Water +Sugar
3: Aluminum +Sulphur
4: Iron + Chromium + Nickle
Answer: 151
151-8611:Zinc + Copper
It will be a mixture called a brass (alloy)
Question: 152
State three reasons why do you think air is a mixture and water a compound
Answer: 152
152-861Air (mixture)
1: Mixture is formed by the simple mixing up of the substances
2: Air does not have a sharp and fixed melting point
3: Air has heterogenous mixture composition
Question: 153
Is atomic mass unit a SI unit of an atomic mass ?
Answer: 153
153-861Yes ,atomic mass unit is SI unit of atomic mass
Question: 154
How many atoms of hydrogen present in one mole of water ?
Answer: 154
154-861One molecule of water is made up of two atoms of hydrogen and 1 atom of oxygen , hence 2×6.02×1023.atoms of hydrogen and6.02×1023 atoms of oxygen constitute one mole of water
Question: 155
Write example of use of radioactive isotopes in the field of medicine and radiotherapy
Answer: 155
155-861In the field of medicine isotopes of iodine I -131 are used for diagnosis of goiter in thyroid gland . While P-32 and Sr 90 are used in the field of radioactivity
Question: 156
What isAvogadro's number?
Answer: 156
156-861Avogadro, s Number:
The number of particles present in one mole of a substance is called Avogadro's number. Its value is 6.02 x 10²³. it is represented by Na
Question: 157
Write down the name of particles which determine the mass of an electron .
Answer: 157
157-861The proton and neutron determine the mass of an atom
Question: 158
Describe the number of molecules in 9 g water.
Answer: 158
158-861Volume of water = 9g
Question: 159
Who discovered proton and neutron ?
Answer: 159
159-861Proton is discovered by Goldstein in 1886
Question: 160
Define relative atomicmass based on C-12 scale.
Answer: 160
160-861Relative Atomic Mass:
The relative atomic mass of an element is the average mass of atoms of the element as compare to 1/11th the mass of one atom of carbon 12 isotope
Question: 161
Differentiate between molecular mass and formula mas , which of the following is molecular formula ?
. H2O
.NaCl
.Kl
.H2SO4
Answer: 161
161-861Molecular mass :
The sum of atomic masses of all the atoms present in one molecule of a molecular compound is its molecular mass
Question: 162
Whether the density of gases increase on cooling ?
Answer: 162
162-861The density of gases increasing by cooling because their volume decreases and molecules of gases came close to each other
Question: 163
How does homogenous mixture differ from heterogenous mixture ?
Answer: 163
163-861Homogenous mixture : Mixtures that have uniform composition through are called homogenous mixture
Question: 164
Define electronic configuration . Also give example .
Answer: 164
164-861The distribution of electrons around the nucleus in various shells and sub shells according to their increasing energy is called electronic configuration.
Question: 165
Which has more atoms :10g of Al or 10 g of Fe ?
Answer: 165
165-86110 g of A 1 has more atoms than 10 g of Fe
For A 1
Question: 166
Write down the number and names of subshell in N-shell .
Answer: 166
166-861Number of sub shell in N shell is 4 named as s ,p ,d and f
Question: 167
Write down chemical reaction of sodium with H2 and Cl2 .
Answer: 167
167-861Reaction of hydrogen with sodium :
Sodium reacts with hydrogen at high temperature to form hydrides
2 Na + H2➜ 2NaH
Question: 168
Differentiate between substance and mixture .
Answer: 168
168-861Substance : A piece of matter in pure form is termed as substance
e,g Glucose (C6H12O6 ) Oxygen
Question: 169
Describe difference between Rutherford's theory and Bohr's atomic theory .
Answer: 169
169-861Rutherford's atomic theory
1: It was based upon classical theory
2: Electrons revolve around the nucleus
3: Atoms should produce continuous spectrum
4: Atoms should collapse
Question: 170
Define relative atomic mass .
Answer: 170
170-861Relative atomic mass of an element is the average masses of atoms of that element as compared to 1 / 12th the mass of one atom of carbon -12 isotope
Question: 171
What is a plum pudding theory ?
Answer: 171
171-861Thomson put forth his plum pudding theory . He postulated that atoms were solid structure of positively charge with tiny negative particle stuck inside . It is like plum in a pudding
Question: 172
Which term is used to represent the mass of 1 mole of molecules of a substance ?
Answer: 172
172-861Gram molecular mass
Question: 173
Define empirical formula and give example .
Answer: 173
173-861It is the simplest whole number , ratio of atoms present in a compound
Question: 174
For what purpose C-14 is used ?
Answer: 174
174-861Uses of C-14
Question: 175
In the basis of properties , elements are divided into which group ?
Answer: 175
175-861On the basis of properties elements are divided into metals , non-metals and metalloids
Question: 176
Which of the following cases the number of hydrogen atoms is more?
Answer: 176
176-8611 mole of NH3 has more hydrogen atoms than 2 moles of HCL
Question: 177
Differentiate between shell and sub shell and give example .
Answer: 177
177-861Sub shell :
1: Every main energy level or shell which have sub energy level (s) or shell are called sub shell
2: They are represented by small letter s, p, and f
Question: 178
Define pascal .It is the unit of which quantity ?
Answer: 178
178-861If one newton force is applied on 1m2area then pressure is called one pascal . It is unit of pressure
Question: 179
Wrote the observations made by Rutherford .
Answer: 179
179-861Observations made by Rutherford are as follows :
Question: 180
Why atomic mass of an atom is defined as relative atomic mass ?
Answer: 180
180-861Atomic mass of an atom is defined as a relative atomic mass , because atomic mass of an atom is the mass which compares or relates with 1/12th mass of carbon 12 isotope
Question: 181
What is maximum capacity of a metal ?
Answer: 181
181-8611: K shall can accommodate 2 electrons
Question: 182
Which six elements constitute 99% of body mass and what are their percentages ?
Answer: 182
182-861Following six elements constitute 99%of body mass
Oxygen 65%
Hydrogen 10%
Calcium 1.5 %
Carbon 18%
Nitrogen 3%
Phosphorous 1.5%
Question: 183
Which one has more molecules : 9 g of water or 9 g of sugar C12 H22 O11 ?
Answer: 183
183-8619g of water has more molecules than 9 g of sugar because moles of water are more than sugar
For water
Question: 184
What is the nature of charge on cathode ray ?
Answer: 184
184-861Cathode rays are deflected toward positive plate in an electric field showing that they are negatively charged
Question: 185
Give the composition of milk .
Answer: 185
185-861Milk is a mixture of calcium , water ,sugar , fat , proteins , minerals, salts , and vitamins
Question: 186
Write down atomic number of nitrogen and oxygen .
Answer: 186
186-861The atomic no of N2 is = 7
Question: 187
Write two properties of covalent compounds
Answer: 187
187-8611: They have usually low melting and boiling points
Question: 188
Explain why are oxygen and hydrogen considered elements whereas water as a compound ?
Answer: 188
188-861Hydrogen and oxygen are element because
1: Each one of it consists of same type of atoms
Question: 189
What are cathode rays ? Who discovered it?
Answer: 189
189-861In 1897 JJ Thomson discovered cathode rays
Question: 190
Why melting point and boiling points of ionic compounds are high?
Answer: 190
190-861Melting and boiling of ionic compounds are high because thy consists of positive and negative ions . There exists very strong electrostatic interaction between these charged ions . That is why a lot of force is required to break these forces
Question: 191
What are two defects in Rutherford's atomic model ?
Answer: 191
191-8611: According to classical theory of radiation , electrons being the charged particles should release or emit energy continuously and they should ultimately fall into the nucleus
Question: 192
How is the periodicity of properties depends upon the number of proton in an atom ?
Answer: 192
192-861Periodicity of properties depends upon the atomic number . Atomic number is defined as total number of protons and nutron in a nucleus of any atom . That's the reason periodicity of properties depend upon protons
Question: 193
Classify the following into elements , compound and mixture ?
1: He and H2
2: CO and Co
3: Water and milk
4: Gold and brass
5: Iron and steel
Answer: 193
193-861Elements :
He , H2 ,Co, Gold , Iron
Question: 194
Define effusion . Give example .
Answer: 194
194-861Effusion : Effusion is defined as the escaping of gas molecules through tiny holes into a space with lesser pressure
Question: 195
Which one has more formula units : 1g of NaClor 1 g KCL ?
Answer: 195
195-861NaCl has more formula units than KCl
For NaCl
Formula unit = Mass / Formula mass
= 1/58.5
= 0.017
Question: 196
Write two properties of gases
Answer: 196
196-8611: Molecules of gases are always in state of continuous motion . They have very high K.E .
Question: 197
Where does most of the mass of an atom exists ?
Answer: 197
197-861Most of the mass of an atom exists in its nucleus . The sum of masses of protons and neutrons is equal to atomic mas of an atom
Question: 198
Differentiate between homoatomic and heteroatomic molecules with examples .
Answer: 198
198-861Homoatomic molecules : A molecule containing same type of atoms is called homoatomic molecule
Question: 199
Write electronic configuration of Sulphur .
Answer: 199
199-861Electronic configuration of Sulphur :
Question: 200
Why the liquid molecules are mobile ?
Answer: 200
200-861Liquid molecule have less intermolecular forces as compared to solids , which are not able to stable molecules of liquid at a fixed points . That is why liquid molecules are mobile
Question: 201
Write electronic configuration of Mg
Answer: 201
201-861Atomic number of Mg 12
Question: 202
Differentiate between empirical and molecular formula .
Answer: 202
202-861Empirical formula: It is the simplest whole number ratio of atoms present in a compound
Question: 203
Define Mendeleev's periodic law .
Answer: 203
203-861Mendeleev arranged the known elements (63) in the order of increasing atomic masses in the horizontal rows called periods . So that elements with similar properties were in the same vertical columns . This arrangement of elements was called periodic table . According toMendeleev's periodic law properties of the element are periodic function of their atomic masses
Question: 204
Why the bond between an electropositive and electronegative atom is ionic in nature ?
Answer: 204
204-861Electropositive elements lose electrons while electronegative elements gain electrons . That's why both combine and forms ionic bond
Question: 205
Write electronic configuration of Chloride ion Cl-
Answer: 205
205-861Electronic configuration of Chloride ion
Question: 206
Why metals are good conductor of electricity ?
Answer: 206
206-861Metals are good conductors of heat and electricity in solid and liquid state due to mobile electrons
Question: 207
Why does 10 g nitrogen gas contain the same number of molecules as 10g of carbon monoxide ?
Answer: 207
207-861Number of moles of nitrogen gas = 10/28 =0.35mol
Number of molecules of N2 = 0.35x0.22x1023
=2.107x1023
Question: 208
Why the rate of diffusion gases is rapid than that of liquids ?
Answer: 208
208-861The rate of diffusion of gases is rapid than that of liquid due to the less attractive forces among the gas molecules than liquids . Gas molecule moves randomly and spread around
Question: 209
How many electrons will be in M shell of an atom having atomic no 15?
Answer: 209
209-861Atomic number 15
K shall = 2 electrons
L shall = 8 electrons
M shall = 5 electrons
Question: 210
In which unit body temperature is measured ?
Answer: 210
210-861Body temperature is measured in fahrenheit scale
Question: 211
Write down the two postulates of Bohr's atomic model .
Answer: 211
211-8611: The hydrogen atom consists of a tiny nucleus and electrons are revolving in one of circular orbits of radius ' r ' around the nucleus
Question: 212
What elements do the following compound contains ?
Answer: 212
212-861Sugar ,common salt , lime water and chalk
Question: 213
Why ionic compounds are easy soluble in water?
Answer: 213
213-861Water is polar compound while ionic compound dissolves and forms cation and anion . Cation makes force of attraction with negative pole of water , while anion with positive pole of water and dissolve in water
Question: 214
Calculate the value of angular momentum of 1st orbit where mvr = nh/2π
Answer: 214
214-861Let angular momentum (mvr) of first orbit is =mvr = nh/2π
Question: 215
Why volume of gas decreases with increase of pressure ?
Answer: 215
215-861Volume of gas decreases with increase of pressure because of empty spaces between their molecules . When gases are compressed the molecules come closer to one another and occupy less volume as compared to the volume in uncompressed state .
Question: 216
What is valency ?
Answer: 216
216-861The combining capacity of an element with other element is called valency
Question: 217
Write down the electronic configuration of following
1: Na 2: Al
Answer: 217
217-8611: Atomic number of Na 11
11Na = 1s2. 2s2 . 2p6 . 3s1
Question: 218
What do you mean by 1 atom of C and 1 gram of atom of C ?
Answer: 218
218-861One atom of carbon has its atomic mass which is 12 amu . But when this mass of carbon atom atom is expressed in grams then it is known as gram atomic mass . As 1 gram of carbon = 12.0 g
Question: 219
Explain any two factors that effect the diffusion .
Answer: 219
219-861Factors effecting in diffusion :
1 :Size of molecules : Big sized molecules diffuse slowly
Question: 220
Write down electronic configuration of phosphorous .
Answer: 220
220-861Atomic number of phosphorous is 15 Electronic configuration is given as below :
Question: 221
What are meant by coordinate covalent compounds ?
Answer: 221
221-8611: Properties of coordinate covalent compounds are similar to those of covalent compounds . They are unsoluble in water , don't ionize so make solution on dissolving in organic solvent
Question: 222
Define chemistry ?
Answer: 222
222-861The branch of science which deals with the composition , structure , properties and reactions of matter is called chemistry .
Question: 223
Write electronic configuration of Boron .
Answer: 223
223-861Atomic no of Boron 5
Question: 224
What are the uses of nuclear chemistry ?
Answer: 224
224-861It has vast application in medical treatment , preservation of food , and generation of electrical power nuclear reactors
Question: 225
Differentiate between homogenous and heterogenous mixture .
Answer: 225
225-861Homogenous Mixture : Mixtures that have have uniform composition throughout are calledhomogenous mixture
Question: 226
Write down any two properties of metals .
Answer: 226
226-8611: They show metallic luster
Question: 227
Which isotopes are called radioactive isotopes ?
Answer: 227
227-861The isotopes have ability to emit radiation naturally called radioactive isotopes
Question: 228
What is meant by variable valency ?
Answer: 228
228-861Some elements show more than one combining power (valency) that is called variable valency
Question: 229
Briefly describe the mobility of gases.
Answer: 229
229-861Gas molecules are always in state of continuous motion . They can move from one place to another because gas molecules have high kinetic energy . This continuous motion of gases is called mobility of gases
Question: 230
Why elements of group 1 and group 2 are called S block elements?
Answer: 230
230-861There are four blocks in the periodic table named after the name of the subshell which is in the process of completion by electrons .
Question: 231
What is radical ?
Answer: 231
231-861An atom or a group of atoms that have some charge and keeps in contact during a chemical reaction is called a radical e,g Hydronium H3O+ and CO3 -2
Question: 232
Write any two properties of covalent compounds .
Answer: 232
232-8611: Properties of coordinate covalent compounds are similar to those of covalent compounds . They are unsoluble in water and don't ionize so make solution on solving in organic solvent
Question: 233
How mass number of same elements are different ?
Answer: 233
233-861Isotopes of an element have same number of protons and electrons but different number of neutrons . That's why isotopes of an element have different atomic masses . Although atomic number remains same
Question: 234
How can you justify that air is a homogenous mixture . Identify substance present in it ?
Answer: 234
234-861Air is a mixture formed by the physical mixing of the substance like nitrogen , oxygen ,carbon dioxide , noble gases and moisture and it has same composition throughout , so it is homogenous mixture
Question: 235
Write down uses of radioactive isotopes as traces for diagnosis and medicine .
Answer: 235
235-8611: The radioactive isotopes are used as tracer to diagnose the presence of tumor inside the body
Question: 236
What ammendment was made by H.Moseley in mendeleev periodic table ?
Answer: 236
236-861According to mendleeve's periodic table properties of the element are periodic function of their atomic mass . Whereas according to H . Moseley's ammendments of periodic law properties of the elements are periodic function of their atomic numbers . This shows an atomic number of an element is equal to the number of electrons in a neutral atom . So atomic number provides the basis of electronic configuration as well .
Question: 237
Define standard atmosphere pressure and write its unit .
Answer: 237
237-861The pressure exerted by a mercury column of 760mm at sea level called standard atmospheric pressure
Question: 238
Name one solid , one liquid and one gaseous element present at room temperature ?
Answer: 238
238-861Sodium ( Na) , Iron ( Fe)
Question: 239
What is the difference between diffusion and effusion ?
Answer: 239
239-861Diffusion: The spontaneous mixing of molecules by random motion and collision of gases form homogenous mixture is called diffusion
Question: 240
Why densities of gases are less than liquids ?
Answer: 240
240-861Gases have low density than liquids and solids . It is due to light mass and more volume occupied by the gas molecules . Gas density is expressed in grams per dm3. Whereas liquid and solid densities are expressed in grams per cm3 i-e liquids and solids are 1000 time denser than gases
Question: 241
Find out molecular mass and formula masses of the following
Na2SO4 ,ZnSO4 , and CuCO3.
Answer: 241
241-861Formula mass of Na2SO4 = 2(23)+32+4 (16)
= 46+32+64
=142 amu
=142 amu
Question: 242
Write electronic configuration of Neon and Berylium
Answer: 242
242-861Atomic number of Neon 10
Question: 243
Define pressure and write its unit .
Answer: 243
243-861Pressure : It is defined as the force exerted by per unit surface area
Question: 244
How many sub shell are there in second sub shell ?
Answer: 244
244-861In second sub shell 'L ' has two sub shells s and p
Question: 245
For what purpose is U-235 used ?
Answer: 245
245-861The radioactive isotopes are used to generate electricity by carrying out controlled nuclear fission reaction in nuclear reactions e.g U-235 is bombarded with slow moving neutrons . The uranium breaks to produce Barium - 139 and Krypton - 94 and three neutrons . A large amount of energy is released which is used to convert water into steam boilers . The steam drives the turbine to generate electricity . This is the peaceful use of atomic energy
Question: 246
Write two properties of ionic compound .
Answer: 246
246-8611: Ionic compound are mostly crystalline solid
Question: 247
Give few properties of cathode rays .
Answer: 247
247-861a: These rays travel in a straight line perpendicular to the cathode surface
Question: 248
Define Boyle's law .
Answer: 248
248-861According to Boyle's law the volume of a given mass of a gas is inversely proportional to its pressure at constant temperature .
Question: 249
Define carbondating .
Answer: 249
249-8611: The radioactive isotopes are used to estimate the age of fossils like dead plants and animals and stones etc . The age determination of very old objects based on the half-lives of the radioactive isotopes is called radioactive isotopes is called radioactive-isotopes dating
Question: 250
How many amu 1 g of a substance has ?
Answer: 250
250-8611.66x 10-24g +1 amu
1g = 1/1.66x 10-24amu
Question: 251
Write down electronic configuration of sodium .
Answer: 251
251-861Electronic configuration of sodium
11Na = 1s2 , 2s2 , 2p6 , 3s1
Question: 252
What is meant by malleability ?
Answer: 252
252-861Malleabilityis the property by virtue of which a metal can be drawn into sheets
Question: 253
What is free radical ? Give example.
Answer: 253
253-861Free radical : Free radical are atoms or groups of atoms possessing odd number (unpaired ) electrons.
Question: 254
Write down the electronic configuration of fluorine and Neon
Answer: 254
254-861Electronic configuration of fluorine:
9F=1s2 , 2s2 , 2p4
Question: 255
Define Dynamic equilibrium ?
Answer: 255
255-861When the rate of evaporation becomes equal to rate of condensation . At that stage the number of molecules evaporating will be equal to the number of molecules coming back (condensing) to liquid . This state is called Dynamic equilibrium
Question: 256
What is atomic number of Sulphur ? Write down its electronic configuration .
Answer: 256
256-861Atomic number of Sulphur IS 16 .
Question: 257
What is difference between Mendeleev's periodic law and modern periodic law?
Answer: 257
257-861Mendeleev's periodic law : The properties of elements are the periodic function of atomic masses
Question: 258
How many atoms are present in one gram atomic mass of a substance ?
Answer: 258
258-861One gram atomic mass of a substance is equal to Avogadro's number in which 6.023x1023atoms are present
Question: 259
What is absolute temperature scale ?
Answer: 259
259-861Lord kelvin introduced obsolute temperature scale or kelvin scale . The scale of temperature starts from 0K or -273.15°Cwhich is given as a name of absolute zero . It is the temperature at which an ideal gas would have zero volume
Question: 260
What is the relationship between mass and mole of a substance ?
Answer: 260
260-861the relationship between mass and mole of a substance is given as following
Question: 261
Define triads and law of octaves .
Answer: 261
261-861Triads : The group of three elements called triads . In these groups central and middle element had atomic mass average of the other two element
Question: 262
Differentiate between molecule or molecular ion ?
Answer: 262
262-861Molecule :
1: It is the smallest particle of a compound which can exist independently and shows all the properties of that compound
2: It is always neutral
3: It is formed by the combination of atoms
4: It is a stable unit
Question: 263
Name the elements of first group .
Answer: 263
263-8611: Hydrogen (H)
Question: 264
Ionic bond is stronger than covalent bond . Explain .
Answer: 264
264-861Ionic bond formed between two opposite charges and electrostatic forces . That's why ionic compound is stronger than covalent bond
Question: 265
What is the atomic number , how it is represented ?
Answer: 265
265-861The atomic number of an element is equal to the number of protons present in the nucleus of its atoms
Question: 266
Write two properties of liquid state of matter
Answer: 266
266-8611: Liquid have fixed volume but no fixed shape . It attains the shape of container in which it is kept
Question: 267
Differentiate between ions and free radicals ?
Answer: 267
267-861Ions :
1: These are atoms which bear some charge
2: They exists in solution or in crystal lattice
3: Their formation is not affected by the presence of light
Question: 268
Why does atomic size increases in a group ?
Answer: 268
268-861The size of atoms or their radii increases from top to bottom in a group . It is because a new shell of electrons is added up the successive period . Which the effect of nuclear charge
Question: 269
What is the affect of temperature on vapour pressure ?
Answer: 269
269-861By increasing temperature , vapour pressure increases and by decreasing temperature vapour pressure decreases
Question: 270
Write down the position of hydrogen in the periodic table
Answer: 270
270-861First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period
Question: 271
What is the significance of chemical formula ?
Answer: 271
271-8611: It represents the name of the substance e.g H2O (water)
Question: 272
Write down the position of hydrogen in the periodic table
Answer: 272
272-861First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period
Question: 273
Find out the mass of 3 moles of oxygen atoms .
Answer: 273
273-8613x16 = 48g of oxygen are present in 3 moles
Question: 274
How many neutrons are there in C-12 , C-13 ?
Answer: 274
274-8611: C-12 has 06 neutrons
2: C-13 has 07 neutrons
Question: 275
What is matter ? How many states it has ?
Answer: 275
275-861Matter is any thing that has mass and occupies space .
Question: 276
For what purpose P-32 and Sr - 90 are used .
Answer: 276
276-8611: For the treatment of skin cancer , isotopes like P-32 and Sr-90 are used because they emit less penetrating beta radiations
Question: 277
Why drops of rain fall downward?
Answer: 277
277-861The density of liquid depends upon its mass and volume . Liquids are denser than gases because molecules of liquid are closely packed and the space between their molecules are negligible . As the liquid molecules have strong intermolecular forces hence they cannot expand freely and have a fixed volume . Like gases they cannot occupy all the available volume of the container that is the reason why densities of liquid are high
Question: 278
How many times is 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams
Answer: 278
278-861One mole of oxygen atom is 16 times heavier than the one mole of hydrogen
Question: 279
Explain Dobereiner's triads .
Answer: 279
279-861Dobereiner observed relationship between atomic masses of several groups of three elements called triads . In these groups , the central or middle element had atomic mass average of the other two elements
Question: 280
Why ionization energy of Na is less than Mg ?
Answer: 280
280-861Ionization energy of Na is less than Mg because Mg has greater nuclear charge than Na and also have smaller size
Question: 281
Define evaporation and give example ?
Answer: 281
281-861Evaporation: The conversion of liquid into vapours called evaporation .
Question: 282
Convert -45°C to kelvin temperature .
Answer: 282
282-861(T)K = (T)°C +273
(T)K = (-45)°C +273
(T)K = (-45+ 273)°C
(T)K = 228
Question: 283
Define biochemistry ?
Answer: 283
283-861It is the branch of chemistry in which we study the structure , composition , and chemical reaction of substances found in living organisms (i-e humans ,animals and plants )
Question: 284
What are trends of ionization energy in periodic table ?
Answer: 284
284-861Ionization energy increases from left to right in the period while it decreases from to bottom in a group
Question: 285
Convert 560 torr into cmHg
Answer: 285
285-8611 torr = 1mm Hg
Question: 286
Define atom according to Dalton ?
Answer: 286
286-861Atom is an indivisible , hard ,dense and sphere
Question: 287
Differentiate between atom and ion ?
Answer: 287
287-861Atom :
1: It is the smallest particle of an element
2: It can or cannot exists independently and can take part in a chemical reaction
3: It is electrically neutral
Question: 288
What is charles law ? Write its equation .
Answer: 288
288-861French scientist J.Charles in 1787 , presented his law that states the volume of given mass of a gas is directly proportional to the absolute temperature if the pressure is kept constant
Question: 289
For what purpose , Iodine-131 is used ?
Answer: 289
289-861Isotopes of iodine I-131 is used to diagnose goiter in thyroid
Question: 290
In which branch of chemistry behaviour of gases and liquid is studied ?
Answer: 290
290-861The bahaviour of gases and liquid is studied in the branch of chemistry called physical chemistry
Question: 291
What is kept constant in Charles law ?
Answer: 291
291-861Pressure is kept constant in Charles law
Question: 292
How many atoms are present in 16g of Oand of S ?
Answer: 292
292-86116 grams of oxygen has 6.022x1023atoms and 8 grams of sulphur has 1.055x1023 atoms
Question: 293
What is meant by periodic function ?
Answer: 293
293-861Repetition of properties due to increases of atomic number after regular intervals in the periodic table is called periodic function
Question: 294
What is the relationship between atomic number and atomic mass ?
Answer: 294
294-861The relationship between atomic number and atomic mass is as following
A = Z+n
Where A = mass number
Z = atomic number
N = no of electrons
Question: 295
Why the elements of group 13 to group 18 are called P block elements ?
Answer: 295
295-861Elements of group 13 to 18 have their valence electrons in P subshell . Therefore , they are called as P-block elements
Question: 296
Give few properties of canal rays .
Answer: 296
296-861a: Deflection of these rays in electric and magnetic field proved that these were positively charged
Question: 297
What is vapour pressure ?
Answer: 297
297-861The pressure exerted by the vapour of a liquid at equilibrium with the liquid at a particular temperature is called vapour pressure of liquid
Question: 298
How are elements are arranged in 4th period ?
Answer: 298
298-861In fourth period 18 elements are arranged in the ascending order of their atomic number
Question: 299
Is the Boyle's law applicable to liquid ? Give reason .
Answer: 299
299-861No we can not apply Boyle's law to liquid because in them intermolecular distance is very less and they are highly incompressible so the effect of pressure does'nt effect much on liquids . That's why we can not apply Boyle's law to liquids
Question: 300
How many atoms of sodium are present in 3 moles of sodium and what is the mass of it ?
Answer: 300
300-861Number of atoms of sodium are present in 3 moles = 3x6.02x1023 atoms
= 1.806x 1024
Question: 301
Why does evaporation increases with the increase in temperature ?
Answer: 301
301-861Evaporation increase with the increase of temperature because at high temperature K.E of the molecules increase so high that they overcome the intermolecular forces and evaporate rapidly
Question: 302
How many atoms are in 1 amu and 1g of hydrogen (H)?
Answer: 302
302-8611amu and 1 gram of hydrogen (H) has 6.022x1023 atoms and 8 grams of sulphur has 1.005x1023atoms
Question: 303
What is difference between Duplet rule and octet rule ?
Answer: 303
303-861Duplet rule : Attaining two electrons in the valence shell is called duplet rule
Question: 304
What is the nature of charge on cathode rays ?
Answer: 304
304-861Their deflection in electric and magnetic field proves that they have negative charge
Question: 305
Differentiate shell and sub-shell with example of each ?
Answer: 305
305-861Shell (Orbit):
The circular orbits of specific energy are called shells or energy levels
Question: 306
Write two uses of isotopes
Answer: 306
306-8611: In the field of medicine isotopes of iodine 131 are use for diagnose of goiter in thyroid gland
Question: 307
How many normal periods are and name also?
Answer: 307
307-8612nd and 3rd periods are known as normal periods and they are two in number
Question: 308
Which branch of chemistry deals with preparation of paints and papers ?
Answer: 308
308-861Industrial chemistry deals with preparation of paints and papers .
Question: 309
How many molecules of water are present in half mole of water ?
Answer: 309
309-861Water molecules in half moles = 1/2x6.02x1023
= 3.01x1023 molecules
Question: 310
Define Newland octaves law ?
Answer: 310
310-861In 1864 British chemist Newlands put forward his observations in the form of law of octaves . He noted that there was a repetition in chemical properties of every eight element if they are arranged by their increasing atomic masses
Question: 311
What is meant by condensation ?
Answer: 311
311-861The returns of the vapours into liquids state on cooling is called condensation
Question: 312
Magnesium has electronic configuration 2,8,2 .Why magnesium tend to lose electron ?
Answer: 312
312-861electronic configuration of magnesium is 2,8,2 . There are 2 electrons in its valence shell . It lose 2 electrons and get stable electronic configuration like noble gas Ne
Question: 313
Define freezing point ?
Answer: 313
313-861The temperature at which liquid and solid coexist at dynamic equilibrium is called freezing point
Question: 314
Differentiate between boiling and melting point .
Answer: 314
314-861Melting point : The temperature at which the solid starts melting and exist in dynamic equilibrium with liquid state is called melting point
Question: 315
What is compressibility?
Answer: 315
315-861Decrease of volume by increasing pressure is called compressibility of that thing like gases . Gases are highly compressible due to empty spaces between their molecules
Question: 316
How many blocks are present in periodic table ?
Answer: 316
316-861There are4 presentin periodic table called s, p, d and f block
Question: 317
The atomic symbol of a phosphorous ion is given as 3115P3-
a : How many protons , electrons , and neutrons are there in ion3115P3- ?
b: What is the name of ion ?
c:Draw electronic configuration of ion .
d: Name noble gas which has some electronic configuration as phosphorous ?
Answer: 317
317-861Proton = 15
Electron = 18
Neutron = 16
b: Phosphorous ion
c: E.C =1s2 , 2s2 , 2p6 , 3s2 ,3p6
Question: 318
Convert 30°Cto kelvin temperature
Answer: 318
318-861We know that
(T)K = (T)°C +273
by putting the values of C°=30° we have
(T)K = (30)°C +273
(T)K = (30+273)°C
(T)K = 303
Question: 319
What is difference between group and period ?
Answer: 319
319-861Group : The vertical columns present in periodic table are called groups .There are 18 groups present in the periodic table
Question: 320
Differentiate between Lone pair and bond pair of electrons .
Answer: 320
320-861Long pair : The pair of electrons which remain unshared during covalent bond formation is called long pair
Question: 321
Why does evaporation cause cooling ?
Answer: 321
321-861When the high kinetic energy molecules evaporates from the surface of liquid , the temperature of the remaining molecules falls down . To compensate the energy decrease , the molecules absorb heat from surrounding falls down and we feel cooling
Question: 322
Is the mass of 1 mole of O and 1 mole of S same ?
Answer: 322
322-861Nothe mass of 1 mole of O and 1 mole of S is not same
Question: 323
Show the state of Dynamic equilibrium in liquid and vapours with the help of diagram .
Answer: 323
323-861From the open surface of a liquid , molecules evaporates and mix up with the air but when we close a system ,evaporated molecules start gathering over the liquid surface . Initially the vapours condense slowly to return to liquid . After sometimes condensation process increases and a stage reaches when the rate of evaporation becomes equal to rate of condensation . At that stage the number of molecules coming back (condensing) to liquid . This state is called Dynamic equilibrium
Question: 324
Why elements are called s and p block elements ?
Answer: 324
324-861Elements are called s and p block elementsbecause their last element is present in s and p sub shell
Question: 325
Identify the following as empirical or molecular formula :
H2O2 ,CH4 , C6H12O6 , C12H22O11 ,BaCO3 ,KBr
Answer: 325
325-861Empirical formula : KBr , BaCO3 , CH4
Question: 326
Define solution with example .
Answer: 326
326-861A solution is a homogenous mixture of two or more substances . The boundaries of compounds can not be distinguished i-e solution exists as one phase
Question: 327
Which branch of chemistry deals with energy of atoms and its uses in daily life ?
Answer: 327
327-861Nuclear chemistry deals with energy of atoms and its uses in daily life
Question: 328
Which branch of chemistry deals with the structure and properties of naturally occurring molecules ?
Answer: 328
328-861Organic chemistry deals with the structure and properties of naturally occurring molecules
Question: 329
What are the elements arranged in group 3 to 12 called ?
Answer: 329
329-861The groups 3 to 12 are called transition elements . In these elements 'd ' sub shell is in the process completion
Question: 330
Why covalent bond in H2 is non-polar ?
Answer: 330
330-861In H2 covalent bond is formed between two similar atoms , the shared pair of electron is attracted by both atoms equally , so non-polar covalent bond exist between hydrogen atoms
Question: 331
Name the element of 1st period of periodic table
Answer: 331
331-8611st period consists only two elements hydrogen (H2|) and Helium ( He)
Question: 332
What is the relationship between empirical formula and formula unit ?
Answer: 332
332-861All the ionic compounds are represented by formula unit . Formula unit is also and empirical formula of ionic compounds
Question: 333
Can pure gold be used for making ornaments?If not why?
Answer: 333
333-861No. pure gold cannot be used for making ornaments.
because gold is too sift to be used as such It is always alloyed with copper. silver and some other metals
Question: 334
What are two factors on which evaporation depends ?
Answer: 334
334-861Surface area : Evaporation is a surface phenomenon . Greater is surface area greater is evaporation
Question: 335
Define single covalent bond and give one example .
Answer: 335
335-861'When one electron is contributed by each bonded atom ,one bond pair is formed and it forms a single covalent bond '
Question: 336
An element has an atomic number 17 , how many electrons are present in K and M shells of an atom ?
Answer: 336
336-861K=2 , L= 8 , M=7
An atom has atomic number 17, in first shell (K) contains 2 electrons , then second shell called (L) shell have 8 electron and 3rd shell (M) have 7 electrons
Question: 337
What is meant by atomic radius ? What is its unit ?
Answer: 337
337-861The half of the distance between the nuclei of two of similar adjacent (bonded) atoms is called atomic radius
Question: 338
Why silver is not used in pure form ?
Answer: 338
338-861Silver is a very soft metal that's why it is not used as such in pure
Question: 339
Why size of an atom decreases from left to right in the periodic table?
Answer: 339
339-861When we move from left to right in a periodic atomic number increase yet the size of atoms decrease gradually . It is because with the increase of atomic number and nuclear charge
Question: 340
In which branch of chemistry are the metabolic processes of carbohydrates and proteins studied ?
Answer: 340
340-861In biochemistry metabolic processes carbohydrates and proteins are studied
Question: 341
How many groups and period and periods are there in modern periodic table
Answer: 341
341-8611: Long form of periodic table consists of seven horizontal rows called periods
Question: 342
What is quantum ?
Answer: 342
342-861Quantum means fixed energy . It is the smallest amount of energy that can be emitted or absorbed as electromagnetic radiation
Question: 343
Define melting point ?
Answer: 343
343-861The temperature at which the solid starts melting and exists in dynamic equilibrium with liquid state is called melting point
Question: 344
How can we distinguish a metal from non-metal by a simple physical method ?
Answer: 344
344-861Metals : On heating metals usually become soft and flexible
They are difficult to cut
Question: 345
What is the empirical formula of acetic acid (CH3COOH)? Also calculate the molecular mass of acetic acid .
Answer: 345
345-861Empirical formula of acetic acid is CH2O
Question: 346
Write down the trend of atomic size in the periodic table.
Answer: 346
346-861In period : Atomic size in a period from left to right decreases
Question: 347
What is the electronegativity of hydrogen and chlorine ?
Answer: 347
347-8611: Value of electronegativity of hydrogen (H) is 22
Question: 348
Define biotechnology?
Answer: 348
348-861It deals practical of living organism to make substances for the welfare of mankind
Question: 349
Why Lanthanides an Actanides are placed separately below periodic table . Explain
Answer: 349
349-861Because of space problem in periodic table two series of elements were placed separately below the normal periodic table to keep it in a manageable and presentable form . Since the two series start after Lanthanum (z=57) and Actinum (z=89) , so these two series of elements are named as Lanthanides and Actanides
Question: 350
Write the names of two allotropic forms of sulphur .
Answer: 350
350-861The allotropic forms of sulphur are given below :
Question: 351
What is periodic law?
Answer: 351
351-861In 1913, H. Moseley observed that atomic number instead of atomic mass should determine the position of elements in the periodic table and according the periodic law was amended as properties of elements are periodic function of their atomic numbers
Question: 352
Write symbol of any four elements of halogen .
Answer: 352
352-8611: Flourine (F)
Question: 353
What is solid-liquid solution ? Explain with example .
Answer: 353
353-861When a solid dissolves in liquid and form solution called solid-liquid solution . If sugar dissolve in water it will be called solid-liquid solution.
Question: 354
Magnesium has electronic configuration 2,8,2
a: How many electrons are in outermost shell ?
b: In which sub-shell of outermost shell electrons are present ?
c: Why magnesium tends to lose electron ?
Answer: 354
354-861a: There are two electrons in outermost shell
b : In sub-shell of outermost shell electron are present
1s2 , 2s2 , 2p6 .3s2
Question: 355
Define unsaturated solution .
Answer: 355
355-861The solution which have capacity to dissolve more amount of solute is called unsaturated solution
Question: 356
Why the 2nd ionization energy is greater than 1st ionization energy ?
Answer: 356
356-861Because after the removal of the first electron from the atom , its number of protons , become greater than electrons . The force of attraction between the nucleus and remaining valence shell electron increases . So more energy is required to remove the 2nd electron from the atom
Question: 357
What is an electron affinity ? Give an example .
Answer: 357
357-861Trend in a group : In a group electron affinity values decreases from top to bottom because the size of an atom increases down the group . With the increase in size of atom shielding effect increase that results in poor attraction for the incoming electron i-e less energy is released out
Question: 358
Convert -30°C to K unit
Answer: 358
358-861As we know that
(T)k = (T)°C +273
By putting°C=-30°
(T)k = (-30)°C +273
(T)k = (-30+273)°C
(T)k = 243°C
Question: 359
Define noble gases and give example .
Answer: 359
359-861Elements of group 18 are called Noble gases
All noble gases have completely filled outermost shells . This is because of this reason , they do not sow any chemical reactivity . They are chemically inert
Question: 360
What is difference between short period and ling period ?
Answer: 360
360-861Short period : First period of periodic table is called short period . It consists of Hydrogen and Helium
Question: 361
What will be the nature of charge on an atom when it loses an electron or when it gains an electron ?
Answer: 361
361-861When it lose an electron it become positive an when it gains and electron it become negative
Question: 362
Define Shielding effect.
Answer: 362
362-861The force of attraction between the nucleus and valence electrons is reduced due to the presence of internal - sell electrons , This effect is called shielding effect
Question: 363
How much amount of KOH required to form 1 molar solution ?
Answer: 363
363-861Concentration of solution = 1dm3
Molar mass of KOH = 39+16+1
= 56 mol
Question: 364
How electro positivity depends upon size and nuclear charge of an atom?
Answer: 364
364-861Electropositivity depends upon size and nuclear charge of an atom because when the size of atoms increases. Electropositivity increases as it becomes easier to lose electrons. It also depends upon nuclear charge if nuclear energy increase the electropositivity decreases because it becomes difficult to remove the electrons from outermost shell
Question: 365
From which word atom derived ?
Answer: 365
365-861Atom is derived from latin word 'Atomos' meaning indivisible
Question: 366
Why ionization energy decreases in a group from top to bottom ?
Answer: 366
366-861When we move down the group in periodic table , more and more shells lie between the valence shell and nucleus of the atom , these additional shells reduce the electrostatic force felt by electrons present in the outermost shell . Resultantly the valence shell electrons can be taken away easily . Therefore , ionization energy of elements decreases from top to bottom in the groups
Question: 367
Differentiate between crystalline and amorphous solid .
Answer: 367
367-861Crystalline solid : Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solid
Question: 368
Do you know any element having no neutron in its atom ?
Answer: 368
368-861Isotope of hydrogen , protium have one proton and no neutrons in it
Question: 369
Write the symbol of noble gasses
Answer: 369
369-8611: Helium (He)
Question: 370
Write down the electronic configuration of Al3+. How many electrons are present in its outer most shells
Answer: 370
370-861Al3+ = 1s2 ,2s2 ,2p6
Question: 371
Why sodium metal is more reactive than magnesium metal?
Answer: 371
371-861Sodium metal is more reactive than magnesium metal because electro-positivity of met increase along the periods from left to right in periodic table. Element in the start of the period are more metallic or electropositive. Across the period from left to right size of atoms decreases due to increase in nuclear charge. That's why, sodium is more reactive than magnesium.
Question: 372
What is electronegativity ? Write its unit .
Answer: 372
372-861The ability of an atom to attract the shared pair of electrons towards itself in a molecule is called electronegativity
Question: 373
Write two properties of crystalline solids .
Answer: 373
373-8611: In crystalline solids particles are arranged in definite in definite pattern .
Question: 374
For what purpose U-235 is used ?
Answer: 374
374-861When U-235 is bombarded with slow moving neutrons , uranium nucleus breaks up to produce Barium-139 and Krypton -94 and three neutrons
Question: 375
What is meant by true solution ?
Answer: 375
375-861True solution are the homogeneous mixture of two or more than two components . Each components is mixed in such a way that their individual identity is not visible
Question: 376
What is meant by octet rule ?
Answer: 376
376-861Attaining 8 electrons in the outermost shell either by sharing by losing or gaining electrons is called octet rule . Atoms complete their octet by gaining , giving or sharing valence electrons with other atoms
Question: 377
What was the pressure inside the discharge tube in discovery of electron?
Answer: 377
377-861The pressure inside the tube was kept 10-4 atm
Question: 378
Why solid show rapidly ?
Answer: 378
378-861The particles of solids are fixed at their position and are not mobile . Therefore they have rigid structure and definite shape .
Question: 379
Why oxygen is called non-metal?
Answer: 379
379-861Non-metals form negative ions by gaining electrons. Oxygen atoms can accept 2 electrons therefore its valency is 2. 0+2e-➜0-2
Question: 380
Define chemical bond and write names of its type .
Answer: 380
380-861A chemical bond is defined as as a force of attraction between atoms that holds them together in a molecules . In other words , during bond formation there is some force which holds the atomic together
Question: 381
If 16g of oxygen contains 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams
Answer: 381
381-86116g of oxygen =1 mol of oxygen
Mass of one atom of oxygen = 16 grams
Question: 382
Describe trend of shielding effect in periodic table .
Answer: 382
382-861The shielding effect increase down the group in the periodic table . Because of this it is easy to take away electron in potassium (Z=19) than from sodium (Z=11) atoms . Similarly the shielding effect decrease in a period if we move from left to right
Question: 383
Define Crystalline solids and give two examples .
Answer: 383
383-861Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solids
Question: 384
What was the thickness of gild foil used in Rutherford's atomic model ?
Answer: 384
384-8610.00004 cm thick gold foil was used by Rutherford in his experiment
Question: 385
Define shielding effect , Describe its trend in a period
Answer: 385
385-861Shielding effect : The force of attraction between the nucleus and valence electrons is reduced due to the presence of internal - shell electrons (core electrons ) This is called shielding effect
Question: 386
Define the coordinate covalent bond? Explain with one example .
Answer: 386
386-861Coordinate covalent bond or dative bonding is a type of covalent bonding in which the bond pair of electrons is donated by one bonded atom only . Coordinate covalent bond is also known as Dative covalent bond
Question: 387
Why does true solutions not show Tyndall effects?
Answer: 387
387-861True solutions not show Tyndall effectsbecause particle are so small that they can not scatter the the rays of light, thus do
not show tyndall effect.
Question: 388
Why is gold used to make jewelry?
Answer: 388
388-861Gold is very nonreactive or inert metal. It is not affected by atmosphere. It is not affected by any single mineral acid or base. It is most malleable and ductile of all the metals. Due these reasons the gold is used to make jewelry.
Question: 389
On which two factors vapour pressure of any liquid depends ?
Answer: 389
389-861Vapour pressure of liquid depends upon following factors :
Question: 390
Why shielding effect of electron makes cation formation easy ?
Answer: 390
390-861Shielding effect reduce the effective nuclear charge due to the nucleus thus the net force on the valence electrons decrease due to higher shielding effect . That is why the removal of valence electron become easy for cation formation
Question: 391
What is the sign of stability of an atom ?
Answer: 391
391-861The sign of stability of an atom IS achieving the electronic configuration similar to noble gases (He , Ne , or Ar etc) i-e (n2 p6 ) or having two or eight electrons in their valence shell . In other words an atom is called stable if it follows duplet or octet rule
Question: 392
Define oxidation and give example .
Answer: 392
392-861Oxidation reaction : The loss of electron by an atom or ion is called oxidation .
Question: 393
What is difference between electron affinity and electron -negativity ?
Answer: 393
393-861Electron affinity : Energy emitted due to the absorption of an electron in gaseous atom of an element is called electron affinity .
Question: 394
How meat can be preserved ?
Answer: 394
394-861Table salt is the most important ingredient for curing meat and is used in large quantities . Salt kills and inhibits the growth of putrefying bacteria by drawing water out of the meat . Concentrations of salt up to 20% are required to kill most of the species of unwanted bacteria . Once properly salted , the meat contains enough salt to prevent the growth of many undesirable microbes
Question: 395
Define effective nuclear charge .
Answer: 395
395-861In an atom , attraction of outer most electrons around the nucleus is decreased due to inner electrons . In result , an atom faces less nucleus charge then the original
Question: 396
Why is the formula of solute necessary for calculation of the molarity of the solution ?
Answer: 396
396-861Formula of solute is necessary for calculation of the molarity of the solution because molarity depends upon No. of moles of solute
Question: 397
Why the trend of electron affinity and electron -negativity same in the period?
Answer: 397
397-861The electron -negativity and electron affinity , both depends upon the size of atom and the nuclear charge . In the period from left to right the nuclear size decreases and nuclear charge increases . Therefore the trend of both is same
Question: 398
Two hydrogen atoms combine to form molecules H2 while 'He' atom remains monatomic . Explain ?
Answer: 398
398-861Two hydrogen atoms combine to form molecules H2 while 'He' atom remains monatomic because the outer most shell of hydrogen is incomplete . On the other hand outer most shell of He is complete
Question: 399
How was it shown that atomic nuclei are positively charged ?
Answer: 399
399-861The deflection of a few particles proved that there is a center of positive charge in an atom , , which is called nucleus of an atom
Question: 400
Write two properties of non-polar covalent compounds .
Answer: 400
400-8611: They do not undergo charge separation
Question: 401
What is the capacity of the K,L,M,N shells ?
Answer: 401
401-861K shell can accommodate 2 electron
L shell can accommodate 8 electrons
M shell can accommodate 18 electrons
N shell accommodate 32 electrons
Question: 402
Differentiate between donor atom and acceptor atom.
Answer: 402
402-861Donor atom : The atom which donates the electron pair in coordinate covalent bond is called donor atom
Question: 403
Describe endothermic reaction with example .
Answer: 403
403-861Endothermic reactions are those reactions in which heat is absorbed in theses reactions test tubes becomes cold
Question: 404
How was it is proved that whole mass of an atom is located at its center ?
Answer: 404
404-861The complete rebounce of a few particles show that the nucleus is very hard , dense and contain all mass of an atom
Question: 405
Which are long periods ? How many elements are present in long periods ?
Answer: 405
405-8614th and 5th periods of the long firm of table are called long periods of periodic table . Both these periods consists on 18 elemensts present in each
Question: 406
What is the reason of deficiency of electrons in BF3?
Answer: 406
406-861In the formation ofBF3molecules , three valence electrons of boron (B) make three pairs of mutual coordination with three valance electrons from three fluorine atoms .. Despite of covalent bond made due to this mutual coordination , there is still deficiency of electron in boron . That's why octate is still incomplete (BF3)
Question: 407
Why silver and gold are least reactive?
Answer: 407
407-861Silver and gold are least reactive because these metals do not lose their electrons easily. They do not have the tendency to make cations and due to their soft nature. They cannot be used as such.
Question: 408
What is the trend of electronegativity in the period ?
Answer: 408
408-861The trend ofelectronegativity is same as of ionization energy and electron affinity . It increases in a period from left to right because higher Zeff shortens distance from the nucleus of the shared pair of electrons . This enhances the shared pair of electron
Question: 409
Explain how anode rays are formed from the gas taken in the discharge tube .
Answer: 409
409-861Anode rays are produced when the cathode rays collide with residual gas molecules present in the discharge tube and ionize them as follows
M+ le-➜ M+ +2e-
Question: 410
Give the reason for the decrease of electronegatively in down the group .
Answer: 410
410-861Electronegatively decreases down a group because size of the atom increases . The attraction for the shared pair of electrons weakens
Question: 411
How can you justify that milk is a colloid?
Answer: 411
411-861Milk is a colloid . It can be justified on the basis of tyndall effect . Itsa solute particles are larger but not enough and can't seen by naked eye amd not settled down after long time and show tyndall effect , So milk is colloid
Question: 412
Define ionization energy .
Answer: 412
412-861Ionization energy is the minimum amount of energy required to remove the most loosely bound electron from the valence shell of an isolated gaseous atom
Question: 413
Why does sodium form a chemical bond with chlorine ?
Answer: 413
413-861Sodium become Na by losing an electron and eight electrons remains in its valence shell . Chlorine gain an electron and becomes Cl-ion . Both these ions attract each other and become stable
Question: 414
Write two uses of redox reaction .
Answer: 414
414-861Redox reaction are useful in batteries to produce energy and this electricity is used to drive non-spontaneous reaction
Question: 415
What observations were the observations made by Rutherford ?
Answer: 415
415-861There were two observations .
Question: 416
Define non polar covalent bond and give example .
Answer: 416
416-861Non polar covalent bond is formed between two similar atoms the hsred pair of electrons is attracted by both the atom equally
Question: 417
Write the simplest way to distinguish between solution and pure liquid .
Answer: 417
417-861The simplest way to distinguish between a solution and a pure liquid is evaporation . The liquid which evaporates completely , leaving no residue , is a pure compound , while a liquid which leaves behind a residue on evaporation is solution
Question: 418
Why metallic character decrease along a period and increase in a group?
Answer: 418
418-861Along the period: Metallic character decreases along the period from left to right.
Reason:
1:. From left to right size of atom decreases and nuclear charge increases so is difficult to remove electron and electropositivity decreases.
Question: 419
Name the particle which determine the mass of an atom ?
Answer: 419
419-861Protons and neutrons determine the mass of an atom
Question: 420
What are spontaneous and non- spontaneous reaction ? Differentiate them
Answer: 420
420-861Spontaneous reaction : The reaction which proceed without any external assistance and heat are called spontaneous reaction .These reactions takes place in galvanic cells
Question: 421
What do you know about the construction of an electrolytic cell?
Answer: 421
421-861An electrolytic cell consists of solution of an electrolyte two electrodes (anode, cathode)that are dipped in the electrolytic solution and connected to the battery . The electrode connected to positive terminal is called anode and electrode connected to the negative terminal is called cathode
Question: 422
A patient has goiter . How will it be detected ?
Answer: 422
422-861The radioactivity isotopes are used as tracers in medicine to diagnose the presence of tumor in human body . Isotope of I-131 is used for diagnose of goiter in thyroid gland
Question: 423
Why solution is considered mixture ?
Answer: 423
423-861The chemical reaction did not take place between the components of solution and the components kept constant their properties . That's way solution is considered mixture .
Question: 424
Why does chlorine accept an electron and attain -1 charge ?
Answer: 424
424-861Chlorine have seven electrons in its valence shell . It require one electron to complete its valence shell . That's why chlorine accept an electron and attain -1 charge
Question: 425
What is meant by metallic bond ?
Answer: 425
425-861When positively charged metal ions are held together by freely moving electrons , the bond which is formed called metallic bond
Question: 426
What is by-products are produced in Down's cell?
Answer: 426
426-861Chlorine is produce in the downs cell as a by product
Question: 427
What is difference between solution and mixture ?
Answer: 427
427-861Solution : Homogenous mixture of two or more substance called solution
Question: 428
Why is HF a weak acid ?
Answer: 428
428-861HF less ionizes , hydrogen bond is present between its molecules . That is why it is a weak acid
Question: 429
Determine the oxidation number of Mn in KMnO4.
Answer: 429
429-861{O.N k } + {O.N Mn } +4 {O.N O} =0
{+1} + {O.N Mn } +4 {-2 } =0
1+ {O.N Mn } 8=0
O.N Mn = 8-1
= 7
Question: 430
How many atoms of hydrogen present in 1 mole of water ?
Answer: 430
430-8611 mole of water = 6.02 x 1023molecules
1 mole of water has H atom =1x 6.02x1023atoms
= 6.02 x 1023
Question: 431
Which compounds of halogens are stable ?
Answer: 431
431-861Halogens form very stable compounds with alkali metals
Question: 432
Differentiate between ionic bond and covalent bond .
Answer: 432
432-861Ionic Bond :
The type of chemical bond which is formed due to complete transfer of electron from one atom to another atom is called ionic bond
Question: 433
Define hydrogen bonding ?
Answer: 433
433-861Th partially positive charged hydrogen atom of one molecule attracts and forms a bond with partially negatively charged atom of the other molecule the bonding is called hydrogen bonding
Question: 434
Why does Aluminium not rust ? Explain
Answer: 434
434-861Aluminium corrodes but it does not rust because a very hard material aluminium oxide , protects the aluminium from rust and further corrosion . Rust refers only to iron and steel corrosion . Whenever , iron corrodes its colour changes that exposes iron to further rusting
Question: 435
Define Bond pair ?
Answer: 435
435-861The valence electrons which take part in covalent bond is called bonding electrons . These electrons present in the incomplete valence shell
Question: 436
What is difference between solution aqueous solution ?
Answer: 436
436-861Solution : A solution is a homogenous mixture of two or more substance
Question: 437
Why noble gases are not reactive ?
Answer: 437
437-861The noble gases have 2 or 8 electrons in their valence shells i-e the valence shell of all the noble gases is complete . Their atoms do not have vacant space to accommodate extra electrons , So noble gases are not reactive
Question: 438
What is the trend of variation in densities of alkali metals?
Answer: 438
438-861Densities of alkali metals increases down the group in the periodic table
Question: 439
How is the goiter in thyroid gland detected ?
Answer: 439
439-861Iodine -131 is used fir the diagnosis of goiter in thyroid gland
Question: 440
Why the second ionization energy of magnesium is higher than the first one?
Answer: 440
440-861he l ionization energy of magnesium is high but the 2" ionization energy of magnesium i, very high. It becomes very difficult to remove second electron from the Mg' ion as nuclear charge attracts the remaining electrons strongly. As a result of this attraction size of the ion decreases.
Question: 441
Why magnesium is harder than sodium?
Answer: 441
441-861Magnesium is harder than sodium because in magnesium metallic bonding is stronger. While sodium is relatively soft metal due to weak metallic bonding in their atoms.
Question: 442
In electroplating of silver , from which electrolyte Ag+ come or where they deposit ?
Answer: 442
442-861In the electrolyte of silver (Ag+) comes from anode and deposit on cathode
Question: 443
Define polar covalent bond with example .
Answer: 443
443-861Polar covalent bond is formed between two different atoms when the shared pair of electrons are not attracted equally by bonded atoms. The compounds resulting from covalent bond are called polar compounds
Question: 444
Differentiate between polar and non polar covalent bond .
Answer: 444
444-861Polar covalent bond : Covalent bond is formed between different atoms having different electronegativity between bonded atoms . Due to which one atom get negative and other get positive charge
Question: 445
What is meant by dipole dipole forces of attraction ?
Answer: 445
445-861When partial positive and partial negative charges exists at different positions in a molecule , the adjacent molecules will arrange themselves in such a way that negative end of that molecule comes near to positive end of other molecule . It results in a net forces of attraction between oppositely charged ends of two adjacent molecules . These attractive forces are called dipole - dipole forces
Question: 446
What do you mean by 24 carat gold ?
Answer: 446
446-861Purity of gold is shown by carat that indicates the number of parts by weight of gold that is present in 24 parts of alloy . Twenty four carat gold is pure and it means al the parts of alloy is gold
Question: 447
Electronic configuration of Cl- ion
Answer: 447
447-861Cl-1s2 ,2s2,2p6 ,3s2 ,3p6
Question: 448
Describe difference between concentrated and dilute solution .
Answer: 448
448-861Concentrated solution : The solution which contains relatively large amount of dissolved solute in solution is called concentrated solution
Question: 449
Is triple covalent bond stronger than double covalent bond ? Give reason
Answer: 449
449-861In triple covalent bond , three shared electron pair is involved while double covalent bond is formed between two shared electron pair . The greater number of shared pair electron , the bond will be stronger . That's why triple covalent bond is stronger than double covalent bond
Question: 450
Why does covalent bond become polar?
Answer: 450
450-861If the covalent bond is formed between two different atoms bond pair of electrons will not attracted equally by the bonded atoms . The atom which has greater electronegativity will attract bond pair more towards itself than other atom and hence molecule will become polar
Question: 451
Why HF is a weak acid ?
Answer: 451
451-861HF is a weak acid because in HF -compound . There is strong intermolecular bonding . So, it does not readily ionize in water and release H+ in water the strong acid is that which is readily ionized in water but HF does not easily ionized in water
Question: 452
Why the boiling point of water higher than alcohol?
Answer: 452
452-861Water has ability to form two hydrogen bonds while Ethyle alcohol has ability to form one hydrogen bond . That's why the boiling point of water is higher than alcohol
Question: 453
What are electrolytes or non-electrolytes ?
Answer: 453
453-861Electrolytes : The electrolytes which can conduct electricity in their aqueous solution of fuse form and produce more ions are called electrolytes
Question: 454
State any four physical properties of metals.
Answer: 454
454-861Physical Properties of Metals.
1: Almost all metals are solid except mercury.
2: Metals have high melting and boiling points. .
3:Metals possess metallic luster.
4: Malleable and ductile
Question: 455
Define aqueous solution . Write its components .
Answer: 455
455-861The solution which is formed by dissolving substance in water is called an aqueous solution . Water in the solution always in large amount and are called solvents
Question: 456
When do electrons emit or absorb energy ?
Answer: 456
456-861A long as electron remain in a particular orbit it does not radiate or absorb energy, The energy is emitted or absorbed only when an electron jumps from one orbit to another
Question: 457
What is the difference between the evaporation and boiling point ?
Answer: 457
457-861Evaporation : The process of changing of a liquid into a gas phase is called evaporation .
Question: 458
What do you mean by malleable and ductile ?
Answer: 458
458-861Malleability is the property by virtue of which metals can be drawn into sheets while ductility is the properties by virtue of which a metal can be drawn into wires
Question: 459
What is salt bridge ? What is its basic function ?
Answer: 459
459-861Galvanic cell consists of two half cells, both these half cells are connected by salt bridge
Question: 460
Why ionization energy of Na is less than Mg?
Answer: 460
460-861Ionization energy of Na is less than Mg because Na requires less energy to lose its valence electron than magnesium. Ionization energy is that energy, which is required to remove outermost electrons from the gaseous state of an element.
Question: 461
Write formulas of two ionic compounds which are soluble in water .
Answer: 461
461-861The two ionic compound which are soluble in water are following
Question: 462
Which metal is used for metal work?
Answer: 462
462-861As the metal work. means fire work. The metals are used in fire work due to its characteristic flame colour when they ignite in air . Na"- give golden colour, "Ca" give red colour etc.
Question: 463
What is difference between corrosion and rusting ?
Answer: 463
463-861Corrosion : Corrosion is slow and continuous eating away a metal by the surrounding medium . It is a redox reaction which takes place on metals by the action of air and vapours
Question: 464
How much NaOH is required to prepare its 500cm3 of 0.4m solution?
Answer: 464
464-861Molar mass of NaOH =40gmol-3
Question: 465
What do you mean by horticulture and how it is related agriculture ?
Answer: 465
465-861It deals with the art of gardening . A horticulture works fir the betterment of existing varieties and for the production of new varieties of ornamental plants and fruits plants
Question: 466
What is difference between solute and solvent ?
Answer: 466
466-861Solute : The component of the solution which is present in smaller quantity is called solute
Question: 467
State the physical properties of sodium .
Answer: 467
467-8611: Its melting point is 97°C
Question: 468
Why does oxygen molecule not form a polar covalent bond ?
Answer: 468
468-861In oxygen molecule formed by hydrogen and oxygen and hence there will be electronegativity difference between the oxygen and hydrogen . Due to which oxygen atlain negative and hydrogen atlain positive charge
Question: 469
What is meant by electroplating ?
Answer: 469
469-861Electroplating is depositing of one metal over the other by means of electrolysis
Question: 470
Which factor controls the non-metallic character of the element?
Answer: 470
470-861The non - metallic character of elements is depending upon the electron affinity and electron affinity and electronegativity
Question: 471
Ice floats on the surface of water . Give reason.
Answer: 471
471-861Floating of ice over water is because of hydrogen bonding . The density of ice at0°C (0.917gcm-3) is less that of liquid water at0°C(1.00 gcm-3) In the liquid state water molecules move randomly . However , when water freezes , the molecules arrange themselves in an ordered form , that gives them an open structure . This process expands the molecules , that results in ice being less dense as compared to water
Question: 472
Write down names of elements of first group and second period of the periodic table .
Answer: 472
472-861First group of periodic table consists of hydrogen , lithium , sodium , potassium , rubidium , cesium , francium
Question: 473
What type of solutions butter and smoke are ?
Answer: 473
473-861Solution : Butter , smoke
Question: 474
Why nitrogen forms compounds with alkaline earth metals directly ?
Answer: 474
474-861A alkaline earth metals from stable nitrides when heated with nitrogen
Question: 475
Describe exothermic reaction with example .
Answer: 475
475-861Exothermic reaction are those reactions in which heat is released. In theses reactions test tubes becomes hot . Aqueous solution of calcium oxide (CaO) , lithium sulphate Li2SO4and cerium sulphate Ce2(SO4) are examples of exothermic reactions
Question: 476
What is the relationship between electro positivity and ionization energy ?
Answer: 476
476-861Electronegativity depends upon the ionization energy which is in turn depends upon size and nuclear charge of the atom
Question: 477
Define metal and give two examples .
Answer: 477
477-861The elements which have ability to lose electron and forms cations called metals like Na , K , Ca
Question: 478
What is solid-solid solution ? Give two examples .
Answer: 478
478-861Alloy: When solid solvent and solid solute make solutions it is called solid-solid solution
Question: 479
Why calcium is more electropositive than to magnesium?
Answer: 479
479-861Calcium is more Electropositivity than magnesium because metallic character or electroposltve character or electropositive character down the group increases due to loosely held and can be easily with drawn from their shells.
Question: 480
Define allotropy and give examples .
Answer: 480
480-861The existence of an element in more than one form in same physical state but different chemical properties is called allotropy .
Question: 481
Name the metal which is the poorest conductor of heat ?
Answer: 481
481-861Lead is the poorest conductor of heat
Question: 482
How is periodicity of properties dependent upon the number of protons in an atom ?
Answer: 482
482-861In periodic table from left to right number of protons increases . Due to change in nuclear charge the properties of an atom were found repeating after regular intervals . Hence periodicity of properties dependent upon the number of proton in an atom
Question: 483
Why water is called universal solvent ?
Answer: 483
483-861Water is called universal solvent because it dissolves almost all the solute particles present in the world
Question: 484
Complete the following chemical equation .
Answer: 484
484-861NaO +H2O➜ 2NaOH
Question: 485
What is the difference between steel and stainless steel ?
Answer: 485
485-861Steel is a mixture while stainless steel is an alloy
Question: 486
Define molar solution and give example .
Answer: 486
486-861When one mole of solute is solved on one dm3 of solvent in measuring flask then it is called one molar solution
Question: 487
What is the trend of ionization energy in the group ?
Answer: 487
487-861As we move down the group , more and more shells lie between the valence shell and the nucleus of the atom , these additional shells reduce the electrostatic force felt by the electrons present in the outermost shell . Resultantly the valence shell electrons can be taken away easily . Therefore , ionization energy of elements decreases from top to bottom in a group
Question: 488
Name a metal which exists in liquid form? Ans: All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state
Answer: 488
488-861All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state
Question: 489
What is tyndall effect ? On which factor it depends ?
Answer: 489
489-861Tydnall effect: The particles of colloids are big enough to scatter the beam of light . It is called tydnall effect
Question: 490
How platinum is used as a catalyst in automobiles and what are advantages of this use ?
Answer: 490
490-861Platinum alloyed with palladium and rhodium is used as a catalyst in automobile as catalyst converter . It converts harmful gases into harmless gases
Question: 491
Write two examples of gas into gas solution .
Answer: 491
491-8611:Air
Question: 492
Write difference between saturated solution and unsaturated solution .
Answer: 492
492-861Saturated solution : The solution containing maximum amount of solute at a given temperature is called saturated solution
Question: 493
Give the trend of ionization energy in a period ?
Answer: 493
493-861If we move from left to right in a period the value of ionization energy increases . Because the size of atom reduce and valence electrons are held strongly by the electrostatic force of nucleus . Therefore elements on left side of the periodic table have low ionization energies as compared to those on right side of the periodic table
Question: 494
A long as electron remains in an orbit , it does not emit or absorb energy , when does it emit or absorb energy ?
Answer: 494
494-861When an electron jumps from lower orbit to higher orbit . It absorbs energy and when it jumps from higher orbit to lower orbit . It radiates energy . This change in energy ,
| △E given by following Plank's equation |
Question: 495
Write any four examples of colloidal solution .
Answer: 495
495-8611: Starch
Question: 496
Define reduction .
Answer: 496
496-861Reduction is defined as addition of hydrogen or removal of oxygen during a chemical reaction
Question: 497
Why the ionization energy of Na is more than K?
Answer: 497
497-861Ionization energy of sodium is more than K because down the group electropositive character increases and ionization energy decreases. As it become easier to remove electron' down the group
Question: 498
What is meant by colloid ?
Answer: 498
498-861The solutions in which the solute particles are larger than those solute particles present in true solution but not large enough to be seen with naked eye are called colloid solution . They show tyndal effect
Question: 499
iodine exists in solid state, can it be beaten with hammer to form sheets?
Answer: 499
499-861No, only solid metals have the characteristic to be beaten with hammer to for sheet
Question: 500
What are Dobereiner's triads ?
Answer: 500
500-861A German chemist Dobereiner's observed relationship between atomic masses of several groups of three elements called triads . In triads the central and middle element had atomic mass average of the other two elements
Question: 501
What is meant by ' Like dissolves like'
Answer: 501
501-8611: The general principle of solubility is like dissolve like . The polar substance are soluble substances are soluble in polar solvents . Ionic solids and polar covalent compounds are soluble in water
Question: 502
Give two examples of suspension .
Answer: 502
502-8611: In suspension the undissolved particles are big enough to be seen with the naked eye
Question: 503
Define atomic radius ?
Answer: 503
503-861The half of the distance between the nuclei of the two bonded atoms referred as atomic radius
Question: 504
Why atoms form bond ?
Answer: 504
504-861It is universal rule that everything in this world tend to become more stable . Atoms achieve stability by attaining electronic configuration (ns2 ,np6 ) like noble gases
Question: 505
Name the best ductile and malleable metal ?
Answer: 505
505-861Gold and silver
Question: 506
Write down names of any two moderate reactive metals
Answer: 506
506-8611: Magnesium
Question: 507
What is the capacity of shells ?
Answer: 507
507-861The number of electrons accommodated by the shell called capacity of shell
Question: 508
Identify as colloids and suspensions : paints, jelly, soap solution , milk , milk of magnesia , chalk in water .
Answer: 508
508-861Colloid : Soap solution , Milk , Jelly
Suspension : paints , milk of magnesia , chalk in water
Question: 509
Why is 2nd ionization energy of magnesium very high than its 1st ionization energy
Answer: 509
509-861Second ionization energy of magnesium is very high than its first ionization energy . Because it becomes very difficult to remove second electron from the Mg- ions as the nuclear charge attracts the remaining electrons strongly
Question: 510
Define reduction on the basis of electron and give example .
Answer: 510
510-861Reduction reaction : The gain of electrons by atom or ion is called reduction reaction .
Question: 511
Why is ionization energy of sodium is less than magnesium ?
Answer: 511
511-861Ionization energy of sodium is less than that of magnesium ,because it becomes very difficult to remove second electron from Mg+ ions as nuclear charge attracts the remaining electrons more strongly . In the result of this attraction size of the ion decreases, So all the elements of alkaline earth metals have high ionization energies as compared to alkali metals
Question: 512
How oxygen react with group-2 metals?
Answer: 512
512-861They are less reactive towards oxygen and oxides are formed on heating
Question: 513
Why electro positivity decreases from left to right in a period?
Answer: 513
513-861Electropositivity decreases across the period from left to right. It means elements in the start of periodic are more metallic. This is because of two reasons,
(i) Size of atoms decreases.
(ii) Nuclear charges increases. upon nuclear charge. If nuclear charge increases the Electropositivity decreases because it becomes difficult to remove the electrons from outermost shell
Question: 514
Why do the colloids show tydnall effect ?
Answer: 514
514-861Colloids shows tyndall effect because the particles of
” colloids scatter the path of light rays due to large size.
Question: 515
Describe at least two necessary conditions for the formation of covalent bond .
Answer: 515
515-8611: A covalent bond is formed between two non-metals
Question: 516
Give application of silver ?
Answer: 516
516-8611: Compound of silver are widely used in photographic films
Question: 517
Give two examples of gas in liquid solution .
Answer: 517
517-8611: Fog
Question: 518
Who discovered proton , electron , neutron ?
Answer: 518
518-861In 1886, Goldstein discovered positively charged particles called protons . In 1897 , J.J Thomson found in an atom , the negatively charged particles known as electron . In 1932 James Chadwick discovered neutron
Question: 519
Why valence of chlorine is 1 ?
Answer: 519
519-861The valency of chlorine is 1 and charge is negative because chlorine belongs to 17th group of periodic table . Its electronic configuration is Cl17=1s2,2s2,2p6,3s2,3p5the valence shell of chlorine deficient by one electron . So, it accepts one electron from any metal and gets 1 charge
Question: 520
Write any two properties of solution and suspension
Answer: 520
520-861Solution :
1: A solution is a homogeneous mixture of two or more substances
Question: 521
How electropositivity depends upon the nuclear charge of an atom ?
Answer: 521
521-861Left to right in a period nuclear charge increase but the number of metals remains same thats whyleft to right there is continuous decrease in the size of atoms . Small size atoms have higher nuclear charge and thus have lower electropositivity . Large size atoms have lower nuclear charge so they have high electropositivity , so ability to liise electron is greater large sized atoms. In high nuclear charge it is difficult to lose electron . The electropositivity of elements depends upon the nuclear charge it is difficult to lose electron . The electropositivity of elements depends upon the nuclear charge
Question: 522
How many sub-shells are there in second shells ?
Answer: 522
522-861Two sub-shells s and p are present in second shell L
Question: 523
What is the nature of metal oxide?
Answer: 523
523-861When metals react with oxygen they form metallic oxide, which are basic in nature. 2Mg+02➜2Mg0
Question: 524
If we add 5cm3 of acetone in water to prepare to prepare 90cm3 of aqueous solution .Calculate the concentration (%v/v) of this solution .
Answer: 524
524-861Using the relationship :
Question: 525
Define oxidation in terms of electrons and give an example .
Answer: 525
525-861Oxidation : The loss of electron by an atom or ion is called oxidation
Question: 526
Define transition temperature . Give example .
Answer: 526
526-861The temperature at which one allotropes changes into another is called is called transition temperature
Question: 527
Define redox reaction , Give an example .
Answer: 527
527-861The reaction in which oxidation as well as reduction takes place at a time called redox reaction
Question: 528
Why the second ionization energy of magnesium is higher than than first ?
Answer: 528
528-861Second ionization energy of magnesium is higher than than first , because it is very difficult to remove the second electron from the Mg+ ion due to much nuclear attraction . As a result of this attraction , size of ions decreases . Due to this reason , the second ionization energy of magnesium is higher than the first
Question: 529
Why alkali metals are more reactive than alkaline earth metals ?
Answer: 529
529-861Alkali metals are extremely reactive because of their ns1valence shell electronic configuration . As there is only one electron in their valence shell , it can be easily given out . It is the reason that they are always found in in nature as cations with +1oxidation state . Therefore , they readily form salts with non-metals
Question: 530
Write any two rules for assigning oxidation number .
Answer: 530
530-8611: The oxidation number (O.N) of an ion consisting on a single element is the same as the charge on that ion .
Question: 531
What is general principle of solubility ?
Answer: 531
531-861The general principle of solubility is ' like dissolve like ' . The polar substance dissolve in polar substance and non-polar substances and non-polar substances dissolve in non-polar substance
Question: 532
6: Complete the following chemical equation :
1: Ca + H2 ➜ , 2: Ca + Cl2
Answer: 532
532-861Calcium reacts with hydrogen at high temperature of form hydrides
1: Ca +H2 ➜ CaH2
Question: 533
Why does an electron fill 2p orbital and then 3s and then 3s orbital ?
Answer: 533
533-861As we know that electrons that electrons fill the shells as order of their increasing energy , i-e lower energy level is occupied first then the high energy level and so on . 2p orbital has lower energy than 3s orbital that is why 2p orbital is first filled and then 3s orbital
Question: 534
Can liquid and gases be brittle?
Answer: 534
534-861No, Only solid non-metals are brittle.
Question: 535
What are anode or cathode ?
Answer: 535
535-861Anode : It is the electrode at which the oxidation takes place
Question: 536
What is difference between steel and stainless steel ?
Answer: 536
536-861Steel : Alloy of iron with other metals called steel
Question: 537
Write the names of noble metals .
Answer: 537
537-861The metals which give least reactions are called noble metals
Question: 538
Define electronic configuration ?
Answer: 538
538-861Electronic configuration : The distribution of electrons around the nucleus in various shells and sub-shells according to increasing energy , is called electronic configuration
Question: 539
Give example of two polar compounds and give their chemical formula .
Answer: 539
539-861Following are some examples of two polar compounds :
Question: 540
What is atomic number of phosphorous ? Write down its electronic configuration .
Answer: 540
540-861Atomic number of phosphorous (P) is 15
Electronic configuration
1s2 , 2s2 ,2p6 ,3s2 ,3p3
Question: 541
What type of solution fog and brass are?
Answer: 541
541-8611: Fog is a solution of liquid solute in gas solvent
Question: 542
Define electrolyte . Give an example .
Answer: 542
542-861Electrolyte : The substance which can conduct electricity in their solution or molten states are called electrolytes . Salts and acids are good electrolytes
Question: 543
Why is naphthalene soluble in carbon tetrachloride and not in water ?
Answer: 543
543-861Non -polar covalent substances are soluble in non-polar solvents due to this reason , naphthalene is soluble in carbon tetrachloride and not soluble in water because water is a polar solvent
Question: 544
Why is platinum is used to make jewelry ?
Answer: 544
544-861Platinum is used to make jewelry items because of its unique characteristics like colour , beauty , strength, flexibility and resistance to tarnish . It provides a secure setting for diamonds and other gemstone , enhancing their brilliance
Question: 545
What is the half cell reactions occuring on cathode and anode in Daniel cell ?
Answer: 545
545-861Following reactions occur at cathode and anode in Daniel cell .
Question: 546
Why ionization energies of alkaline earth metals are higher than alkali metals?
Answer: 546
546-861Alkaline earth mewls have higher ionization energies than alkali metals because the electronic configuration of their valence shells is ns2. Their atoms are smaller and have more nuclear charge. That is why. they are reactive but less alkali metals
Question: 547
Why do the isotopes of an element have different atomic number masses?
Answer: 547
547-861As isotopes of an element have same atomic mass . Mass number depends upon number of protons and neutrons . Isotopes of an element have the same number of proton but only differ in their neutrons number
Question: 548
Write down two significance of non-metals
Answer: 548
548-8611: Non-metals are essential part of the body structure of all living things . Human body is made up of about 28 elements . But about 96% of the mass
of the human body is made up of just 4 elements i-e oxygen 65% carbon 18%, hydrogen 10% , and nitrogen 3% . Similarly plant bodies are made up of cellulose,
which is compose of carbon , hydrogen , and oxygen
Question: 549
Write the name of two non-polar solvents .
Answer: 549
549-861Toluene and benzene aretwo non-polar solvents
Question: 550
WHat do you know about the oxidizing characteristics of halogens ?
Answer: 550
550-861Chlorine is the most poweful oxidizing agent. Oxidizing property of halogens is decreased from top to bottom . All halogens react with hydrogen gbas in the
presence of light and catalyst to make halides . Stability of their hydrogen halides are given below
HF > HCL > HBR > HI
Question: 551
What is classical theory of radiation . How it is differ from quantum theory ?
Answer: 551
551-861According to classical theory of radiation electrons being the charge particle should release energy continuously and they should ultimately fall into a nucleus . It differ from quantum theory because quantum means fixed energy it is the smallest amount of energy that can be emitted or absorb as electromagnetic radiation
Question: 552
Give difference between solution and colloids .
Answer: 552
552-861Colloids :
The particles of colloids are large consisting of many atoms , ions , or molecules
Question: 553
Why do ionic compound conduct electricity in solution form . Give reason
Answer: 553
553-861Ionic compounds are found in the form of positive and negative ions when they are in solution or molten form . When these programs are connected through a battery their ions create an opportunity for an electron (charges) to move rapidly and current begins to flow Therefore , this flow of current proved that ionic compounds are good conductors and they conduct electricity in solutions or molten form
Question: 554
What happens to iron in the rusting process ?
Answer: 554
554-861The oxidation of iron take place during rusting process and forms Fe2O3 . The chemical formula of rust is Fe2O3nH2O
Question: 555
How will you test weather given solution is colloidal solution or not ?
Answer: 555
555-861Colloidal solution show tyndall effect and other solutions do not show tyndall effect
Question: 556
Name a metal which can be cut with knife?
Answer: 556
556-861Sodium is that metal which can be cut with knife, because it is soft.
Question: 557
Define solubility ?
Answer: 557
557-861The amount of solute in grams dissolved in 100g of solvent to prepare saturated solution at a particular temperature is called solubility of solute .
Question: 558
Identify strong or weak electrolyte among the following
CuSO4 , H2CO3 ,(OH)2 , AGNO3 , Ca (OH)2
Answer: 558
558-861Strong electrolyte :HCL,HNO3 and CuSO4. AgNO3 are strong electrolyte
Question: 559
Define brine ?
Answer: 559
559-861The by-product in Nelson's cell are hydrogen gas (H2) and chlorine gas (Cl2)
Question: 560
Define transition element ?
Answer: 560
560-861d block elements called transition element
Question: 561
What is effective nuclear charge ?
Answer: 561
561-861The valence electron of an atom experiences less nuclear change than that of actual charge , it is called effective nuclear charge or Zeff
Question: 562
Define molarity and write its equation .
Answer: 562
562-861It is a concentration unit defined as number of moles of solute dissolved in one dm3 of solution . It is represented by M.
Question: 563
Define electrochemical cell . With the names of its types .
Answer: 563
563-861Electrochemical cell is an energy storage device in which either a chemical reaction takes place by using electric current or chemical reaction produces electric current
Question: 564
Define alloy and give example .
Answer: 564
564-861Alloy : alloy is a homogeneous mixture of one metal with one or more metals or non-metals
Question: 565
Why benzene is insoluble in water ?
Answer: 565
565-861The principle of solubility is 'like dissolve like' . Benzene is a non-polar compound whereas water is a polar compound . Due to the reason , benzene is insoluble in water
Question: 566
What is galvanic cell? Give an example .
Answer: 566
566-861The electrochemical cell in which a spontaneous chemical reaction takes place and generates electric current is called galvanic or voltaic cell
Question: 567
What is the nature of electrode used in electroplating chromium ?
Answer: 567
567-861During electroplating chromium the object to be electroplated act as cathode with anode is made up of antiamonial lead
Question: 568
Name the most abundant non- metal in earth's crust?
Answer: 568
568-861Oxygen has has the highest percentage in earth's crust 47% and oceans 86% but second highest percentage in atmosphere 21%
Question: 569
Why we stir paints thoroughlybefore use ?
Answer: 569
569-861Paint is a suspension and there are undissolved particles in the suspension which are seen with naked eye . These particles settled down after some time .That's why we stir paints thoroughly before use
Question: 570
Write the redox reaction taking place during the electroplating of chromium .
Answer: 570
570-861Chromium sulphate Cr(SO4)3 used as an electrolyte in the electroplating of chromium that provides CCr+3 ions which reduce and deposit at cathode
Question: 571
Which solution is used as an electrolyte in Nelson's cell ?
Answer: 571
571-861In Nelson cell concentrated solution of sodium chloride is used . It is called brine solution
Question: 572
Define electrolysis and give example .
Answer: 572
572-861The decomposition of compound by passing electric current through molton or aqueous solution of the compound called electrolysis
Question: 573
Why do suspensions not form the homogeneous mixture ?
Answer: 573
573-861The force of attraction does not develop between particles of solvent and solute in the suspensions , due to this , suspension does not from homogeneous mixture
Question: 574
How chlorine chemical react with dilute ?
Answer: 574
574-861Chlorine react withcold dilute NaCl to give sodium hypochlorite
2NaOH +Cl2 ➜ NaCl +NaOCL + H2O
Question: 575
What is meant by malleable and ductile metals ?
Answer: 575
575-861Malleable : The substance that can be drawn into sheets are called malleable
Question: 576
What is difference between valency and oxidation ?
Answer: 576
576-861Valency : Valency is the combining capacity of an atom with other atoms . It depends upon the number of electrons in the outermost shell
Question: 577
Where sodium metal is obtained from fused sodium chloride .
Answer: 577
577-861Sodium metal accumulates at iron cathode in down's cell
Question: 578
What is metallic coating ?
Answer: 578
578-861For the protection against the rusting metals are coated with other metal and it is called metallic coating.
Question: 579
Write down four important chemical properties of metals .
Answer: 579
579-8611: Metals easily lose electron and form positive ions
Na➜ Na +1 +le-
Question: 580
Calculate the oxidation number of Sulphur (S) in H2SO4
Answer: 580
580-861H2SO4 = 2(+1) +(S) +4(-2)
=2=S-8
S = +6
Question: 581
How is platinum used as a catalyst in automobiles and what are advantages of this use?
Answer: 581
581-861An alloy of platinum. palladium and rhodium is used as catalyst in automobiles as catalytic converter. It converts most of the toxic gases (CO, NO2) being emitted by vehicles into less harmful carbon dioxide. nitrogen and water vapour.
Question: 582
Give two characteristics of colloid .
Answer: 582
582-8611: Colloid particles are large but can't be seen with naked eyes
Question: 583
Why cesium requires little energy to release its one electron present in the their outermost shell ?
Answer: 583
583-861Cesium is the 2nd last element of 1st group . It has large size and less force and less force of attraction between the nucleus and valence electron , as a result small amount of energy is required to remove electron from the valence shell
Question: 584
Write down use of paints and greases .
Answer: 584
584-8611: Greasing or painting of the surface can prevent the corrosion of iron
Question: 585
How many electrons will be in M-shell of an atom having atomic number 15 ?
Answer: 585
585-861K L M
2 8 5
5 electrons are present in M shell of an atom having atomic number 15
Question: 586
Define modern periodic law ?
Answer: 586
586-861In 1913 H.Moseley given Modern law
Properties of elements are periodic function of their atomic masses
Question: 587
Explain the effect of temperature on solubility .
Answer: 587
587-8611: Temperature has major affect on the solubility of most of the substances
Question: 588
Differentiate between homoatomic and heteroatomic molecules with example.
Answer: 588
588-861Homoatomic molecules; A molecule containing same type of atoms is called monatomic molecule.
for example: H2, O3, S8
Question: 589
If an element has atomic number 13 and atomic mass 27 , how many electrons are there in each atom of the element?
Answer: 589
589-861Atomic number of an element (Z) =13
Mass no.of an atom (A) =27
A the total number of electrons in an atom is equal to its atomic number (Z) ,so it will have 3s electrons
Question: 590
Give the characteristics properties of ionic compounds
Answer: 590
590-861the characteristic properties of ionic compounds. %Its: Characteristic Properties of Ionic Compounds: (I) lanai compounds are mostly crystalline solids. In I Ionic compounds in solid state have negligible electrical conductance but they are good conductors in solution and in the molten form. It is due to presence of free inns in them. lilt) Ionic compounds have high melting and boiling point example. NaCI has M.P. 800°C and B.P. 1413°C. (iv) Ionic compounds dissolves in polar solvents. Like NaCI dissolves in water.
Question: 591
Which salt is used as electrolyte in chromium electroplating ?
Answer: 591
591-861In electroplating of chromium Sulphate Cr2(SO4)3 is used an electrolyte
Question: 592
Why are the colloids quite stable ?
Answer: 592
592-861In colloid particles are large but not large enough and they are stabilized hence they do not settle down for a ling time that is why colloids are quite stable
Question: 593
Why is the bond between an electropositive and an electronegative atom ionic in nature ?
Answer: 593
593-861Because ionic bond is formed due to transfer of electron from one atom to another atom is called ionic bond. The elements of Group 1 and Group 2 being metals have the tendency to lose their electrons forming positively charged ions. Whereas non-metals of Group 15 to Group 17 have the tendency to pin or accept electrons. They are electronegative elements with high electron affinities.
Question: 594
Why cesium (At.No.55 ) requires little energy to release its one electron present in their outermost shell ?
Answer: 594
594-861Cesium is the 2nd last element of 1st group . It has large size and less force of attraction between the nucleus and valence electron , as a result small amount of energy is required to remove electron from the valence shell
Question: 595
Write down the reaction of magnesium with oxygen . How oxygen reacts with magnesium ?
Answer: 595
595-861Magnesium reacts with oxygen and magnesium oxide is formed
Question: 596
Define isotope ?
Answer: 596
596-861Isotopes are defined as the atoms of elements that have same atomic number but different mass number
Question: 597
What type of elements form metallic bond?
Answer: 597
597-861Metals form metallic bond
Question: 598
Identify a strong and weak electrolyte among the following compound
- CuSO4 , Ca (OH)2 , HCL , HNO3
Answer: 598
598-861Strong electrolyte :HCL ,HNO3 AND CuSO4 are strong electrolyte
Question: 599
How can you justify that blood is a colloid?
Answer: 599
599-861Blood appears to be a homogenous but actually it is a heterogeneous mixture. Blood particles do not settle down for a long time so we can say that blood is a colloidal solution
n
Question: 600
Why noble gases are non-reactive?
Answer: 600
600-861The noble gases do have 2 or 8 electrons in their valence shells. It means all the noble gases have their valence shells completely filled. Their atoms do not have vacant space in their valence, shell to accommodate extra electrons. Therefore noble gases do not gain. lose or share electrons. that's why they are non - reactive
Question: 601
Define groups ?
Answer: 601
601-861The vertical columns in periodic table are called groups . Numbered from 1 to 18
Question: 602
Complete and balance the given chemical equation Na + H2➜ ?
Answer: 602
602-8612Na + H2➜ 2NaH
(Sodium ) (Hydrogen ) (sodium hydroxide )
Question: 603
Explain plum pudding theory .
Answer: 603
603-861Thomson put forth his plum pudding theory . He postulated that atoms were solid structures of positively charge with tiny negative particles stuck inside . It is like plum in the pudding
Question: 604
Define super-saturated solution .
Answer: 604
604-861The solution that is more concentrated than a saturated solution at a given temperature is known as super- saturated solution
Question: 605
Write down the reaction occuring on cathode and anode during the electrolysis of water .
Answer: 605
605-861Following reactions occur at anode and cathode during electrolysis of water
Question: 606
Define oxidation in terms of oxygen with an example .
Answer: 606
606-861Oxidation : The addition of oxygen in any chemical reaction is called oxidation reaction
Question: 607
Write two physical properties of sodium hydroxide .
Answer: 607
607-8611: NaOH is crystalline solid at room temperature
Question: 608
What is difference between colloidal and suspension ?
Answer: 608
608-861Colloid : The particles of colloid are large consisting of many atoms , ions or molecules . Particles are large but can't be seen with naked eye
Question: 609
How is periodicity of properties dependent upon the numbers of protons in an atom ?
Answer: 609
609-861In periodic table from left to right number of protons increase regularly by 1 from atom to atom . Therefore nuclear charge will increase . Due to change in nuclear charge the properties of an atom were found repeating after regular intervals . Hence periodicity of properties dependent upin the number of protons in an atom
Question: 610
What are weak electrolytes? . Give example .
Answer: 610
610-861The substances which ionize to a small extent when dissolved in water and could not produce more ions are called weak electrolytes
Question: 611
Write two uses of calcium .
Answer: 611
611-8611: It is used to remove sulphur from petroleum products
Question: 612
Why suspension and solutions do not show Tyndnall effect , while colloids do?
Answer: 612
612-861Solution does not show Tyndall effect because their particles are so small that they cannot scatter the ray of light . Suspensions do not show Tyndall effect because their particles are so big that light is blocked and difficult to pass . Colloid shows Tyndall effect because their particles are big enough to scatter the beam of light
Question: 613
Write chemical reaction that takes place during working of Nelson's cell.
Answer: 613
613-861Following reactions take place in Nelson's cell
Ions formed in Brine
2NaCl (aq)➜ 2Na+ (aq) +2Cl(aq)
Question: 614
What do you mean by malleability?
Answer: 614
614-861Malleability is the property by virtue of which metals can be drawn into sheets.
Question: 615
How many electrons are present in sub-shell ?
Answer: 615
615-861s can have 2 electrons
p can have 6 electrons
d can have 10 electrons
f can have 14 electrons
Question: 616
Where do electrons flow from Zn electrode in Daniel's cell ?
Answer: 616
616-861In Daniel's cell electron flow from Zn electrode to Cu electrode i-e from anode to cathode through external circuit
Question: 617
How molar solution is prepared ?
Answer: 617
617-861One molar solution is prepared by dissolving 1 mole of the solute in sufficient water to make the total volume of solution upto 1 dm3 in a measuring flask
Question: 618
Why shielding effect of electrons makes action formation easy ?
Answer: 618
618-861As we move down in a group more and more shells come between valence shell and the nucleus of an atom , additional shell reduce the electrostatic force of attraction felt by the electron present in the outermost shell and the shielding effect increases resultantly , and electrons can be taken away , easily and cations form
Question: 619
Give the electronic configuration of carbon atom.
Answer: 619
619-861Atomic no. of carbon = Z= 6
No of electrons in carbon atom =Z=6
Electronic configuration of carbon atom=ls2.2s2,2p2
Question: 620
What are blocks ? How many blocks are present in periodic table ?
Answer: 620
620-861On the basis of completion of a particular sub shell , element with similar sub-shell electronic configuration are referred as a block of elements . Four blocks are present in periodic table . s,p,d,f
Question: 621
Calculate the oxidation number of chlorine in KClO3 .
Answer: 621
621-861{O.N of K } + {O.N of Cl } +3 {O.N of O } =0
{ +1 } + {O.N of Cl } +3 {-3} = 0
{O.N of Cl} + {1} +{-6} =0
{O.N of Cl } +1-6 =0
O.N of Cl {-5} =0
O.N OF Cl =5
Question: 622
Define corrosion ?
Answer: 622
622-861Corrosion is slow and continuous eating away a metal by the surrounding medium . It is a redox chemical reaction that takes place by the action of air and moisture with metals
Question: 623
Write down names of two very reactive metals .
Answer: 623
623-8611: Li (Lithium)
Question: 624
Define electrochemistry .
Answer: 624
624-861Electrochemistry is a branch of chemistry that deals with the relationship between electricity and chemical reaction
Question: 625
How can you prove that angular momentum is quantized ?
Answer: 625
625-861mvr =nh/2π
The angular momentum of first orbit is (n=1)
mvr = 6.63x10-34/2x 3.14
Question: 626
How will you compare he electropositivity ok alkali metals and alkaline earth metals ?
Answer: 626
626-861:Alkali metal
These are highly electropositive. They have highly ionization energy values ranging from 520k.Jmol 1 for Li to 376 k.Jmol 1 for CS
Alkaline earth metal :They have less ionization energy values ranging from 1787k.Jmol 1 for Be to 936 k.Jmol 1 for Ba
Question: 627
Define Mendeleev's periodic table ?
Answer: 627
627-861A Russian chemist arranged elements (63) discovered at that time according to increasing atomic mass . ' Properties of elements are periodic function of their atomic masses '
Question: 628
Calculate the oxidation number of nitrogen in HNO3 .
Answer: 628
628-861HNO3 = (1) +(N) +3 (-2)
= 1+N-6
N = +5
Question: 629
Why test tube becomes cold when KNO3 is dissolved in water ?
Answer: 629
629-861The dissolution of KNO3 in water is an endothermic process in which heat absorbed when KNO3 dissolve in test tube it becomes cold
Question: 630
What is stainless steel?
Answer: 630
630-861Stainless steel is an alloy which is formed by the combination of iron , ,chromium and nickel
Question: 631
Give electronic configuration of hydrogen ?
Answer: 631
631-861Electronic configuration of 11H is 1s1
Question: 632
Why does a dipole develop in a molecule ?
Answer: 632
632-861The unequal sharing of electrons between two different types of atoms make one end of molecule slightly positive and other end slightly negatively charged . As shared pair of electron is drawn towards more electronegative atom , it is partially negatively charged . The other end automatically becomes partially positively charged
Question: 633
Why the ionic compounds have high melting and boiling points?
Answer: 633
633-861Ionic compounds have high melting and boiling points. As ionic compounds are made up of positive and negative ions, there exist strong electrostatic forces of attraction between oppositely charged ions. So, a great amount of energy is required to break these forces
Question: 634
Complete and balance the following equation Mg +N2➜ ?
Answer: 634
634-8613Mg +N2➜ Mg3N2
(Magnesium ) (Nitrogen) (Magnesium nitride)
Question: 635
Which metal is used for the galvanizing of iron ?
Answer: 635
635-861Zinc metal is used for galvanizing of iron because it protects from corrosion
Question: 636
Define electrolytes and electro chemical cell .
Answer: 636
636-861Electrolytes : The substances , which can conduct electricity in their aqueous solution or molten state , are called electrolytes
Question: 637
Why is the ionization energy of Na more than 'K'?
Answer: 637
637-861The first ionization of Na (495,8kJ/mol ) is greater than first ioniztaion energy of 'K' (418.8kJ(mol) and the atomic size of Na is less than 'K' so the energy required to remove an electron from outermost shell of Na is greater than that ok K ,so the ionization energy of Na is more than k
Question: 638
Give one example each of the use of radioactive isotope in medicine and radiotherapy ?
Answer: 638
638-861Radioactive isotopes is used in medicine
Iodine 131
Radioactive isotopes used in radiotherapy
P-32
Sr-90
Co-60
Question: 639
Differentiate between molecular mass and formula mass, which of the following will be molecular formula?
Answer: 639
639-861H2O,NaCl, KI, H2SO4
Question: 640
What is absolute zero?
Answer: 640
640-861It is the temperature at which an ideal gas would have zero volume.
Question: 641
Write uses of silver .
Answer: 641
641-8611: Being very sift metal , it is rarely used as such . Alloys of silver woth copper are widely used in making coins , silver-ware and ornaments
2: Compiunds of silver are widely used in photographic films and dental preparations
3: Silver also has important applications in mirror industry
Question: 642
Describe difference between true solution and colloid .
Answer: 642
642-861True solution : True solutions are the mixture of homogenous mixture of two or more than two components . Each component is mixed in such a way that their individual identity not visible
Question: 643
How many neutrons are present in C-12 and C-13 ?
Answer: 643
643-861C-12 C-13
P=6 P=6
N=12-6=6 N=13-6=7
Question: 644
Why arc the densities of gases tower than that of liquids?
Answer: 644
644-861Gases has e low density than liquids and solids. It is due to light mass and more volume occupied by the gas molecules.
Question: 645
Which force drives the non-spontaneous reaction to take place ?
Answer: 645
645-861Non-spontaneous reactions are those which take place in the presence of an external agent . These reactions takes place in galvanic and electrolytic cells
Question: 646
What are non - electrolytes .Give one example
Answer: 646
646-861The substances , which do not ionize in their aqueous solutions and do not allow the current to pass through their solutions are called non-electrolytes
Question: 647
What is the colour of flame when sodium and calcium burn in air ?
Answer: 647
647-8611: Sodium burns in air and produce golden yellow flame
Question: 648
How sodium metal is obtained from fused sodium chloride .
Answer: 648
648-861On the industrial scale molten sodium metal is obtained by the electrolysis of fused NaCl in the Down's cell . This electrolytic cell is a circular furnace . In the center of the furnace there is a large block of graphite , which acts as an anode while cathode around it is made of iron
Question: 649
Can, you cool a gas by increasing its volume
Answer: 649
649-861No. we cannot cool a gas by increasing its volume
Question: 650
Why does reactivity of metals increase down the group?
Answer: 650
650-861The reactivity of metals increase down the group due to increase in atomic size and shielding effect down the group . The ability of the metals to loose electrons increase down the group and ionization energy also decrease hence their reactivity increase down the group
Question: 651
What happens at cathode in galvanic cell ?
Answer: 651
651-861Reduction process takes place at cathode in galvanic cell
Cu+2 + 2e➜ Cu
Question: 652
Define oxidation and reduction reaction .
Answer: 652
652-861Oxidation: Oxidation is defined as addition of oxygen or removal of hydrogen or electron during a chemical reaction
Question: 653
Why is vapour pressure higher at high temperature?
Answer: 653
653-861At high temperature, vapour pressure is higher than at low temperature. At elevated temperature, the Kinetic energy of the molecules increases enough to enable them to vaporize and exert pressure.
Question: 654
Define nuclear fission reaction .
Answer: 654
654-861A reaction in which heavy nuclear splits up into two nuclei by absorbing show moving next ions
Question: 655
Write two method for prevention of corrosion .
Answer: 655
655-861Method for prevention of corrosion:
Following are some method from avoiding corrosion
Question: 656
What is the principle of electroplating ?
Answer: 656
656-861Principle of electroplating is to establish an electrolytic cell in which anode is made of the metal to be deposited and cathode of the object on which metal is to deposit . The electrolyte is an aqueous solution of salt of the respective metal
Question: 657
Which variables are kept constant in Charles' law?
Answer: 657
657-861Pressure is kept constant in Charles' law
Question: 658
Molecular formula of a sulphur molecule
Answer: 658
658-861The Molecular formula of a sulphur molecule S8
Question: 659
What is electropositivity ? Explain with example
Answer: 659
659-861Electropositivity : Metals have the tendency to loose their valence electron from their valence shell . The property of the metal is termed as electropositivity or metallic character
Question: 660
How electroplating of zinc is carried out ?
Answer: 660
660-861The target metal is cleaned in alkaline detergent type solutions , and it is treated with acid , in order to remove any rust or surface scales. Next the zinc is deposited on the metal by immersing it in a chemical bath containing electrolyte zinc sulphate . A current is applied , which results in zinc being deposited on the target metal i-e cathode
Question: 661
What are difference between string and weak electrolytes .
Answer: 661
661-861Strong electrolyte : The substance which ionizes completely in solution to produce more ions which can conduct strongly is called strong electrolyte
Question: 662
What is the shape of cathode in the Nelson's cell ? Why is it perforated ?
Answer: 662
662-861The cathode in Nelson's cell is U- shaped . It is perforated for the percolation of NaoH into a catch basin
Question: 663
Which metals are the most malleable and ductile ?
Answer: 663
663-861Gold (Au) is the most malleable and ductile of all metals . One gram of gold can be drawn into a wire of one and called ductile
Question: 664
Describe the non-metallic character in groups and period of a periodic table
Answer: 664
664-861Non-metallic charactyer in groups : In groups electrnegativity decreases from up to top bottom therefore non-metallic characrter alse decreases from top to bottom
Non-metallic charactyer in periods : In periods , electron affinity from left to right , due to which metallic character also increases
Due to this reason , fliorine is most non-metallic element in nature
Question: 665
What is galvanizing ?
Answer: 665
665-8611: The process of coating a thin layer of zinc on iron is called galvanizing
Question: 666
Why shielding effect of electron makes action formation easy ?
Answer: 666
666-861As we move down in a group more and more shells come come between valence shell and the nucleus of atom , additional shell reduce the electrostatic force of attraction felt by the electron present in the outermost shell , and the shielding effect increases resultantly , and the electrons can be taken away , easily and cations form
Question: 667
What are shells ?
Answer: 667
667-861Shells are specific energy levels around nucleus in which electron resolve
e.g K,L,M,N
Question: 668
What are metalloids ? Give two examples .
Answer: 668
668-861The elements whose properties are intermediate between metals and non-metals are called metalloids
Question: 669
Write difference between electrolytic cell and galvanic cell.
Answer: 669
669-861Electrolytic cell :
1: It consists of one complete cell. connected to battery
2: Anode has positive charge while cathode have negative charge
3: Electrical energy is converted into chemical energy
4: Current is used for the non-spontaneous chemical reaction to take place
Question: 670
Difference between substance and mixture.
Answer: 670
670-861Substance: A piece of matter in pure form is termed as substance.
e.g. Glucose (C6H12O6) Oxygen
Question: 671
In which pattern modern periodic table was arranged?
Answer: 671
671-861According to increasing atomic number.
Question: 672
Why copper is used for making electrical wires ?
Answer: 672
672-861Copper is used for making electrical wires because it is highly ductile and least reactive . Copper is among noble metals
Question: 673
Why atomic number is more fundamental property to arrange elements than atomic mass?
Answer: 673
673-861Due to two reasons :
1: It increase regularly from element to element
Question: 674
What does mean rusting of iron ?
Answer: 674
674-861Corrosion of iron is called rusting . The important condition for rusting is moist air
Question: 675
Which carbon isotope use in carbon dating ?
Answer: 675
675-861C-14 used in carbon dating
Question: 676
In which units body temperature is measured ?
Answer: 676
676-861Body temperature is measured in Fahrenheit scales . Normal body temperature is 98.6°F , it is equivalent to 37° C . This temperature is close to average normal atmospheric temperature
Question: 677
How iron is prevented from rust by tin coating ?
Answer: 677
677-8611:It involves the dipping of the clean sheet of iron in a bath of molten tin and then passing it through hot rollers
Question: 678
What do you mean like dissolve like ? Explain with example ?
Answer: 678
678-861The general principle of solubility is , like dissolve like
1: The ionic and polar substance are soluble in polar solvents . ionic solids and polar covalent compounds are soluble in water e.g KCl , Na2CO3, CuSO4etc
Question: 679
Write uses of magnesium .
Answer: 679
679-8611: Magnesium is used in flash light bulbs and in fireworks .
Question: 680
Write any two uses of sodium .
Answer: 680
680-8611:Sodium potassium alloy is used as a coolant in nuclear reactor
Question: 681
Justify with an example the solubility of salt increases with increase in temperature?
Answer: 681
681-861When salts like KNO3, KCl are added in water, the test tube become cold. It means during dissolution of this salts heat is absorbed. Such dissolving process in called endothermic Solvent + Solute + Heat-+Solution Solubility increase with the increase in temperature. It means that heat is required to break attractive forces b/w the ions of solute. This requirement is fulfilled by surrounding molecules.
Question: 682
Why do electrodes get their names "anode" and cathode in galvanic cell?
Answer: 682
682-861In galvanic, cell. Oxidation take place at anode while reduction take place at cathode
Question: 683
Can pure gold be used for making ornaments ? If not , why ?
Answer: 683
683-861Gold is too soft ,to be used as such . That is why it cannot be used aline in making ornaments . It is always alloyed with copper ,silver or some other metals
Question: 684
Define oxidizing and reducing agents with example .
Answer: 684
684-861Oxidizing agent:
1: Oxidizing agent is the species that oxides a substance by taking electrons from it
2: The substance (atom or ion ) which is reduced itself by gaining electrons is also called oxidizing agent
Question: 685
What do you mean by group or median in periodic table ?
Answer: 685
685-861The horizontal rows in periodic table called periods and vertical columns in the periodic table are called groups
Question: 686
Why is calcium more electropositive than magnesium ?
Answer: 686
686-861Calcium is more electropositive than magnesium due to its large atomic size and less amount of ionization energy
Question: 687
Write two physical properties of magnesium .
Answer: 687
687-861Magnesium is good conductor of heat and electricity
Question: 688
Define oxidation state ?
Answer: 688
688-861Oxidation state is the apparent charge assigned to an atom of an element in a molecule or ion
Question: 689
Why an iron grill is painted frequently?
Answer: 689
689-861Iron grill is painted frequently because due to presence of oxygen and water in air. It become, corrode. So to prevent it front rusting it is painted
Question: 690
Why and how are element arranged in 4th period ?
Answer: 690
690-861Elements are arranged in 4th period according to increasing atomic number . The 4th period contains 18 elements beginning with potassium and ending with krypton . As a rule . 4th period elements fill their 4th subshells in that order however there are exception such as chromium
Question: 691
What are the defects of Mendeleev's periodic table or why improvement was make in Mendeleev's periodic table?
Answer: 691
691-861There are two defects in Mendeleev's periodic table:
Question: 692
What are metalloides ? Gibe two examples
Answer: 692
692-861The elements have characteristics of both metals and non-metals are called metalloids
Question: 693
What are electrolytic cell ?
Answer: 693
693-861Electrolytic cell : The type of electrochemical cell in which the non-spontaneous chemical reaction is carried out with the help of electric current is called electrolytic cell
Question: 694
Write chemical reaction of water with bromine .
Answer: 694
694-861bromine only reacts with water under following special condition .
Br2 + H2O ➜ HBr + HOBr
Question: 695
What is the difference between Mendeleev's and modern periodic law ?
Answer: 695
695-861Mendeleev's periodic law :
Properties of the element are periodic function of their atomic masses is called Mendeleev's periodic law
Question: 696
How galvanizing of iron sheets is done ?
Answer: 696
696-861The process of Galvanizing is carried out by dipping a clean iron sheet in a zinc chloride bath and then heating it . After this iron sheet is removed , rolled into molten zinc metal bath and finally air -cooled . Advantages of galvanizing is that zinc protects the iron against corrosion
Question: 697
An element in oxidation state +7 gains electrons to be reduced to oxidation state +2 . How
Answer: 697
697-861Suppose an element X +7
Question: 698
What is pacemaker ?
Answer: 698
698-861A pacemaker is a small device in which body fluids act as an electrolyte . This device uses electrical pulses to prompt the heart to beat at a normal rate
Question: 699
Write two properties of platinum.
Answer: 699
699-8611: Platinum is a noble metal and very least reactive
Question: 700
What are Lanthanide and actinide series ?
Answer: 700
700-861Due to space problem two series of elements are placed below periodic table
Question: 701
Write ant two chemical properties of non-metals .
Answer: 701
701-8611 : Non-metals usually do not react with water
2: They do not react with dilute acids because non-metals are itself electron acceptors
Question: 702
What type of covalent bond is formed in nitrogen molecule?
Answer: 702
702-861In nitrogen molecule. three bond pairs are involved in bond formation. This type is called triple covalent bond. Three small lines are used to indicate these three pairs of electrons between those atoms in the molecules of such compounds.
Question: 703
Write down two uses of gold .
Answer: 703
703-861Because of its inertness in atmosphere , it is an ornamental metal as well as used in making coins . Gold is too soft to be used as such
It is always alloyed with copper, silver or some other metal
Question: 704
Why O2 is necessary for rusting ?
Answer: 704
704-861Rusting is the oxidation of any metal . The important condition for rusting is moist air (air having water vapours formed which is called rust . In the absence of oxygen this reaction did not take place due to which rusting dis not happen
Question: 705
Write down the names of elements of groups 1 with their symbols .
Answer: 705
705-8611st group elements are called alkali metals . It consists of hydrogen (H) , lithium (Li) , sodium (Na) , potassium (K) , rubidium (Rb) and cesium (Cs) , and francium (Fr)
Question: 706
Metals are good conductors of electricity .Why ?
Answer: 706
706-861Metals have free moving electrons called mobile electrons . Due to presence of these electrons metals are good conductors of electricity
Question: 707
Differentiate bonding electrons and non-bonding electrons•
Answer: 707
707-861The valence electrons which are involved in chemical boding, are termed as bonding electrons. e.g.
The valence electron of sodium is bonding electrons
11Na K L M
2 8 1
Question: 708
What are SI units of atomic radius ?
Answer: 708
708-861Pico meter (pm) =10-12m
Question: 709
In electroplating of silver , from which electrolyte Ag+ comes and where they deposit ?
Answer: 709
709-861In the electrolyte of silver (Ag)+ comes from anode and deposit on cathode .
Question: 710
Write four physical properties of calcium metals .
Answer: 710
710-8611: Calcium is silvery grey and fairly harder metal
Question: 711
Why big size covalent molecules have high melting and boiling points?
Answer: 711
711-861Bigger molecules with three dimensional bonding form covalent crystals which are very stable and have high melting and boiling points.
Question: 712
Why sodium metal is more reactive than magnesium ?
Answer: 712
712-861Magnesium is harder then sodium because density of sodium is 0.98cm -3 and density of magnesium is 1.74gcm3 . Sodium is too soft to be cut with knife
Question: 713
What do you mean by delta sign and why it develop ?
Answer: 713
713-861The delta sign indicates partial positive or partial negative charge that is developed due to unequal sharing of shared pair or bonded pair of electrons
Question: 714
Which is most precious metal ?
Answer: 714
714-861The most precious metal is platinum
Question: 715
Why the size of atom does not decrease regularly in periods ?
Answer: 715
715-861The atomic size does not decrease regularly in periods due to presence of transition elements . The size of atom first decreases then increases
Question: 716
Write down names of any four halogens .
Answer: 716
716-8611: Fluorine 2: Chlorine 3: Bromine 4: Iodine
Question: 717
In which form sulphur exists at I00°C?
Answer: 717
717-861Sulphur exists in monoclinic form at 100"C because at room temperature sulphur exists in rhombic form. The transition temperature of sulphur is 96"C at which rhombic sulphur convened into monoclinic form.
Question: 718
Which factors affect the non-metallic character ?
Answer: 718
718-861Non-metallic character depends upon Electron affinity and electronegativity
Question: 719
Define periodicity ?
Answer: 719
719-861Properties of elements were found repeating after regular intervals in periodic table it is the periodicity
Question: 720
Whether the density of a gas decreases on cooling ?
Answer: 720
720-861The density of gas increase by cooling because their volume decreases
Question: 721
Compare two physical properties of metals and non-metals .
Answer: 721
721-861Metal :
1:Almost all metals are solid (except mercury) they have high densities
Question: 722
How many elements are in 3rd period, write their names and symbols?
Answer: 722
722-861There are eight elements in 3' period, sodium(Na), magnesium(Mg) .aluminium (AI).silicon(Si),phosphorus(P),sulphur(S),chlorine(Cl),argon(Ar)
Question: 723
Write down melting point and boiling point of sodium metal .
Answer: 723
723-861Melting and boiling point of sodium metal are as follows
Question: 724
Why 2nd ionization energy of an elements is higher than first one?
Answer: 724
724-861fins: energy required to remove an electron from isolated mono positive gaseous ion (M') is called second ionization energy. So more energy is required to remove second electron from a mono positive gaseous ion because there is more electrostatic force present between the nuclei and electron. M+➜M+21e-
Question: 725
Why are the rates of diffusion in liquids slower than that of gases?
Answer: 725
725-861In liquid molecules intermolecular forces are stronger than gases and there molecules are, closer to each other. Asa result rate of diffusion in liquids are slower than gases.
Question: 726
Write four physical properties of metals
Answer: 726
726-8611: Almost all metals are solid (Except mercury)
Question: 727
Give chemical reaction of methane with chlorine in bright light .
Answer: 727
727-861In bright light (sun light) Cl2 react with CH4 violently and explosively
Chemical reaction : CH4 +2Cl2 ➜ C+4HCL
Question: 728
What is the reason for the difference between solutions, colloids and suspensions?
Answer: 728
728-861Particles of solutions are so small that they can't scattered the rays of light, thus do not show Tyndall effect.
Particles of colloids scatter the path of light rays thus emitting the beam of light i.e. exhibit the Tyndall effect.
Particles of suspension are so big that light is blocked and difficult to pass
Question: 729
An element has 5 electron in M shell . Find out its atomic number ?
Answer: 729
729-861The number of this element will be 15
Question: 730
Why ionization energy ok alkaline earth metals is higher than alkali metals?
Answer: 730
730-861The size of alkali metals is samaller than alkaline earth metals that's why they have high ionization energy
Question: 731
Name the metal which is least conductor of heat ?
Answer: 731
731-861Lead is a metal which is least conductor of heat
Question: 732
Why do atoms react ?
Answer: 732
732-861It is an universal rule that everything in this world tends to become more stable . Atoms achieve stability by attaining electronic configuration of inert gases (He ,Ne ,or Ar ) . Having 2 or 8 electrons in the valence shell is sign of stability . Attaining two electrons in the valence shell is called duplet rule while attaining 8 electrons in the valence shell is called octet rule
Question: 733
Define aqueous solution
Answer: 733
733-861The solution which is formed by dissolving a substance in water is called an aqueous solution
Question: 734
Define metallic character .
Answer: 734
734-861The property of a metal to loose its valence electrons to form a positive ion is called metallic character
Question: 735
What is the significance of water for survival of life .
Answer: 735
735-861Water is an essential compound for the survival of all the living things . It is made up of non-metals .It is not only the major part by mass of the bodies
of living things but it is also essenhtial to maintain the life . We can survive without water for days but not for a long period . Its shortage may cause death
Question: 736
Define periods ?
Answer: 736
736-861Seven horizontal rows present in periodic table are called periods . Numbered from 1 to 7
Question: 737
Write the redox reaction taking place during the electroplating of chromium.
Answer: 737
737-861Reaction at the electrodes are as Follows:
At anode 40H-➜2H2O+O2+4e-
At cathode C+33e-➜Cr
Question: 738
Why do atoms form chemical bonds?
Answer: 738
738-861Atoms achieve stability by attaining electronic configuration of inert gases ns2 or ns2,np6 Atoms combine with one another. which is called chemical bond.
Question: 739
How metallic character is changes in a group of periodic table ?
Answer: 739
739-861Metallic character increase in a group from top to bottom due to increase in the size of atoms
Question: 740
Describe atIeast two necessary conditions for the formation of a covalent bond.
Answer: 740
740-861Iwo necessary conditions for the formation of covalent bond are: (.) The electronegativity difference between atoms must be less. So. that the shared pair of electrons is attracted by both the atoms equally. (i1) Maximum 3 to 6 electrons are present in their valence shells
Question: 741
Describe the chemical reaction of alkaline earth metals with hydrogen .
Answer: 741
741-861Alkaline metals :
Reaction with oxygen :
1: Alkaline metals immediately tarnish in air giving their oxides which form strong alkalies in water
4Na +O➜ 2Na2 O
Na2 O➜ 2NaOH
2: Reaction with hydrogen :
The form ionic hydrides with H2at high temperature
2Na +H2➜2NaH
Reaction with Halogens :
3: They react violently with halogens at room temperature to give halides
2Na +Cl2➜ 2NaCL
Question: 742
What do you mean by induced dipole?
Answer: 742
742-861The charges in one molecule creates charges in other molecules these charges are called induced dipole.
Question: 743
Why nitrogen is necessary for safety of life on earth ?
Answer: 743
743-861Nitrigen is 78% in atmosphere and is necessary for safety of life on earth . It controls the fire and combustion process ,
otherwise all the things around us could burn with a single flame
Question: 744
Why does sodium lose one electron and attain +1 charge?
Answer: 744
744-861Sodium has one electron in its valence shell. So. it loses its outer most electrons to complete its octet and become positive ion .i.e. Na+
Question: 745
Write two properties of silver
Answer: 745
745-8611: Silver is a white Lustrous metal
2: Silver is good conductor of heat and electricity
3: Silver is a very malleable and ductile
Question: 746
Why are dipole forces of attraction not found in halogen molecules?
Answer: 746
746-861Dipole forces of attraction do not found in halogen molecules because they have same electronegativity and there is equal sharing of electrons.
Question: 747
Metals arc good conductor of electricity. Why?
Answer: 747
747-861Metals are good conductors of electricity because metals have free electrons which are mobile in nature. Spaces are present among the atoms. Mobile electrons can move freely in these spaces. (Fence, movement/flow of electrons is known as electricity that's why metals are good conductor of electricity.
Question: 748
How do atoms follow octet rule?
Answer: 748
748-861Atoms follow octet rule to have the noble gas electronic configuration. For this purpose atoms attain 8 electrons in the outermost shell either by sharing. by losing or by gaining electrons
Question: 749
What is relation between electropositivity and ionization energy ?
Answer: 749
749-861Electropositivity is the reverse of the ionization energy . In the from from top to bottom ionization energy decreases and electropositivity increases
Question: 750
Define standard atmospheric pressure . What are its units ? How it is relate to the pascal ?
Answer: 750
750-861It is defined as the pressure exerted by a mercury column of 760 mm height at sea level
Question: 751
What do you means by 24 carat gold ?
Answer: 751
751-8611: Purity of gold is show by carats .
Question: 752
How atoms accommodate 8 electrons in their valence shells?
Answer: 752
752-861toms can accommodate 8 electrons in their valence shell in three.
1: By giving valence shell electrons
2:By gaining valence shell electrons
3:By sharing valence shell electrons with other atoms
Question: 753
Write down the name of four least reactive metals .
Answer: 753
753-861The names of least reactive metals are following
Question: 754
Why is the hold of nucleus over the outermost electrons in metal weak ?
Answer: 754
754-861The hold of nucleus over the outermost electrons is weak because of large size atoms and greater number of shells in between nucleus and valence electrons . Furthermore ,because of low ionization potentials , metals have the tendency to to loose their outermost electrons easily
Question: 755
Write down two properties of gold
Answer: 755
755-8611: Gold is a yellow sift metal
2: It is most malleable and ductile of all the metals
Question: 756
Does Kelvin scale show negative temperature?
Answer: 756
756-861No. Kelvin scale does not show a negative temperature
Question: 757
Why alkali metals are extremenly reactive ?
Answer: 757
757-861Alkali metals : The elements in the first group of the periodic table are calleed alkali metals
Reactive of alkali metals :
Alkali metals are extrmely reactive elements because of their ns 1 valence shell electronic configuration . These metals only have one electronin theor valence shell , which can be easily
given out
Question: 758
Why do ionic compounds conduct electricity in solution or molten form?
Answer: 758
758-861Ionic compounds are good conductor in solution and molten form due to the presence of free ions in them
Question: 759
Define halogens . give example .
Answer: 759
759-861Halogens : The element of group 17 called halogens
Example : Chlorine , Fluorine , Bromine etc
Question: 760
Which is the simplest form of matter?
Answer: 760
760-861Gas is the simplest form of matter.
Question: 761
Give the reaction of mangnesium with O2 And N2 .
Answer: 761
761-861Reaction of magnesium with O2 :
They are less reactive towards oxygen and oxides are formed on heating
2Mg + ➜ 2MgO
Question: 762
What will happen if the pressure temperature is kept constant?
Answer: 762
762-861The volume of gas will decrease three times when its pressure raised up to three times as temperature.
Question: 763
Give uses of platinum
Answer: 763
763-861Uses of platinum :
1: Platinum is used in hard disk coating and in maufacturing fibre optic cables
Question: 764
State whether allotropy is shown by elements or compounds or both ?
Answer: 764
764-861Allotropy is only shown by elements . It is not a property of compounds
Question: 765
What type of bond exists in ionic compound?
Answer: 765
765-861Ionic bond exists in ionic compound.
Question: 766
Which form of Sulphur exists at room temperature?
Answer: 766
766-861Rhombic (S8) Sulphur exists at room temperature
Question: 767
Write names of any two noble metals
Answer: 767
767-8611: Copper
Question: 768
How many elements are in first period and what are their names and symbols?
Answer: 768
768-861There are two elements in first period, hydrogen (H), helium(He)
Question: 769
Why do non-metals accept electron readily ?
Answer: 769
769-861Non-metals have high electronegativity , can accept electrons readily in order to complete their last (valence ) shells
Question: 770
how can you explain the solute-solvent interaction to prepare NaCI Solution?
Answer: 770
770-861When NaCI is added in water it dissolves readily because the attractive interaction between the ions of NaCI and polar molecules of water are strong enough to overcome the attractive forces between Na' and CI- ions in solid NaC1 crystal. In this process the positive end of the water dipole is oriented towards the CF ions and the negative end of water dipole is orwater molecules are so strong that they pull these ions from their positions in the the Na- ions. These ion dipole attractions between Na+ ions and water molecules, Cl- ions and water molecules are so strong that they pull these ions from their positions in the crystal and thus NaCl dissloves
Question: 771
What do you mean by evaporation and how it is affected by surface area?
Answer: 771
771-861Evaporation: The process changing of a liquid into a gas phase is called evaporation.
Surface Area:
Evaporation is a surface phenomenon. Greater is surface area. greater is evaporation and vice versa. For example, sometimes a saucer is used if tea is to cooled quickly. This is because evaporation from larger surface area if saucer is more than that from the small surface area of a as cup.
Question: 772
Why platinum is used as for making jewellery ?
Answer: 772
772-861Platinum is very important metal . It is rust free and nin-reactive with oxygen and other gases which are present in atmosphere . Platinum is used to make .
jewellery items because of its unique properties like colour , beauty , strenght , flexibilty and resistance to tarnish
Question: 773
How platinum is used as a catalyst in automobiles?
Answer: 773
773-861Platinum and rhodium are used as catalyst convertor
Advantages : They convert most of the gases being emitted by vehicles into less harmful carbon dioxide , nitrogen and water vapour
Question: 774
Why are the liquids mobile.
Answer: 774
774-861Liquid molecules are in continuous state of motion. They possess high kinetic energy and have weak intermolecular forces than solids That's why liquids are mobile
Question: 775
Why fluorine is more non-metallic than chlorine ?
Answer: 775
775-861Fluorine is more reactive than chlorine because the electronegativity of fluorine is greater tahn chlorine
Question: 776
How the properties of elements repeat after regular intervals?
Answer: 776
776-861The modern periodic table is based upon the arrangement of elements according to increasing atomic number. When the elements are arranged according to increasing atomic number from left to right in a horizontal row. properties of elements were found repeating after regular intervals
Question: 777
Is sign of (0) used on Kelvin?
Answer: 777
777-861No. Degree sign (°) is used with Celsius scale not with Kelvin scale.
Question: 778
Give chemical reaction of H2 and Cl2 and l2Reaction of H2 with Cl2 :
Answer: 778
778-861H2 reacts with Cl2 only in the presence of sunlight
H2 + Cl2 ➜ 2HCL
Question: 779
Why is galvanizing done?
Answer: 779
779-861The process of coating a thin layer of zinc or iron is called galvanizing. Galvanizing is dot, because zinc protects the iron against corrosion even after the coating surface is broken.
Question: 780
Why volume of a gas decreases with increase of pressure"
Answer: 780
780-861The volume of a given mass of a gas is inversely proportional to the pressure if the temperature is kept constant' therefore while decreasing the volume of gas pressure will increase
Question: 781
Give the non-metallic trend in halogens .
Answer: 781
781-861Elements of group of periodic table consists of fluorine ,chlorine, bromine , iodine . and astatine
Their non-metallic nature decrease down the group . Fuorine is most metallic ,while iodine is least non-metallic
Question: 782
How will you test whenever given solution is colloidal solution or not?
Answer: 782
782-861If the panicles scatter the path of light rays thus emitting the beam of light i.e exhibit the Tyndall effect than the given solution is colloid.
Question: 783
Explain the law of flow of heat ?
Answer: 783
783-861In winter atmospheric temperature falls lower than that of our body temperature . According to principle of heat flow out from our body and we feel cold . To control this outward flow of heat , we wear black and warm clothes . To maintain body temperature we use dry fruits tea, coffee and meats etc
Question: 784
Differentiate between lone pair and bond pair of electron.
Answer: 784
784-861Lone Pair
The non-bonded electron pair available on an atom. like the one lone pair is available on nitrogen in ammonia is called a lone pair
Question: 785
In what conditions H2 reacts with l2 ? Give equation of the reaction .
Answer: 785
785-861H2 reacts with l2 on heating and in the presence of catalyst to produce hydrogen iodide
H2 + l2 ➜ 2Hl
Question: 786
Write reaction of chlorine with hydrogen and water
Answer: 786
786-861Reaction of hydrogen with chlorine
Cl2 +H2O ➜ HCL +HOCL
Question: 787
Why the elements are called s and p block elements?
Answer: 787
787-861The elements having their valence electrons in s and p sub shell called s and p blocks elements.
Question: 788
An element X has oxidation state 0 . What will be the oxidation state when it gains three electrons ?
Answer: 788
788-861Suppose the element x
X0 +3e-➜ X-3
Question: 789
Describes the trends of electropositivity in a period and in a group .
Answer: 789
789-861Electropositive character increase down the group because size of atoms increase and nuclear charge decrease . Electropositive character decreases across the period from left to right because atomic size decrease and nuclear charge increase
Question: 790
What do you mean by %volume/volume
Answer: 790
790-861It is a volume in cm3 of a solute dissolved. per100cm3 of solution. For example 3O% alcohol solution means 30cm3 of alcohol dissolved in sufficient amount of water, so total volume would 100 cm3
Question: 791
What is ionic bond? Give an example.
Answer: 791
791-861Definition: A chemical bond which is formed due to complete transfer of electron from one atom to another atom is called ionic bond.
Question: 792
Ionic compounds conduct electricity in solution or molten form. Why?
Answer: 792
792-861Ionic compounds conduct electricity in solution or molten form because in these two states ionic compounds have free ions in them. When these free ion move in solution or molten gate they become conductor of electricity
Question: 793
Differentiate saturated and unsaturated solution
Answer: 793
793-861Saturated : A solution containing maximum amount of solute at a given temperature is called saturated solution
Question: 794
What is the reason of arranging elements in a group?
Answer: 794
794-861The reason of arranging of elements in a groups, is that they have same electronic configuration and same properties so they form a family.
Question: 795
How a covalent bond becomes polar?
Answer: 795
795-861When a covalent bond is formed between two different atoms having different electronagetivity then the bond pair of electron will not be attracted equally by the bonded atoms as a result partial positive and negative charges appear on atoms and covalent bond becomes polar.
Question: 796
How many members are in group 17, is there any liquid, what is its name?
Answer: 796
796-861There arc five members in group 17 which are F,C1 .Br , I and At. Only one liquid element is present named as bromine Br).
Question: 797
hat is the importance of oxygen and carbon dioxide for plants and animals ?
Answer: 797
797-861Life owes to non-metals as without O2 and CO2 those are essential gases for respiration of animals and plants respectively , life would not have been possible . In fact these
gases are essential for the existance of life
Question: 798
What is the nature of electrode used in electroplating of chromium?
Answer: 798
798-861The object to be electroplated acts as cathode while anode is made of antimonial-lead.
Question: 799
What is a triple covalent bond, explain with an example?
Answer: 799
799-861Ans: When each bonded atom contributes three electrons, three bond pairs are involved in bond formation. This type is called triple covalent bond. Three small lines are used to indicate these three pairs of electrons between those atoms in the molecules of such compounds. For example: Nt & C2H2 Formulas: N.N.H-C==C-H
Question: 800
Differentiate duplet and octet rule.
Answer: 800
800-861Duplet Rule:
Attaining two electrons in valence called duplet rule.
Example. , Li+Hefollow duplet rule.
Question: 801
Why is 02 necessary for rusting?
Answer: 801
801-86102 is necessary for rusting because it acts as oxidizing agent. It first oxidize iron-to Fe+2 ion thus Fe+ ion to rust (Fe203.n H2O) in the presence of water.
Question: 802
Why has water polar covalent bond ?
Answer: 802
802-861Water has polar covalent bonds because there is a difference of electronegativity (1.3) between H and O atoms . There will be an unequal attraction for the bond pair of electron between H and O atoms . It will results in the preparation of polar covalent bond
Question: 803
What is difference between polar and non-polar covalent bonds, explain with one example of each?
Answer: 803
803-861Polar Covalent Bonds Non-Polar Covalent Bonds
If the covalent bond is formed between two different types of atoms then bond pair of electrons will not be attracted equally by the bonded atoms. One of the atoms will attract the bond pair of electrons more strongly than the other one. They form polar covalent bond. For example: H+—F', H+—CI-
Question: 804
Why silver and gold are least reactive ?
Answer: 804
804-861From the transition metals of group 11 of periodic table Silover and Gold are least reactive because they do not lose electron easily
Question: 805
Considering the electronic configuration of nitrogen atom, how many electrons are involved in bond formation and w hat type of covalent bond is formed?
Answer: 805
805-861Electronic configuration of N is 1s2.2s2.2p3 Nitrogen has 5 electrons in its valence shell. Three electrons are involved in bond formation and triple covalent bond is formed.: N = N :
Question: 806
What is the relationship between evaporation and boiling point of a liquid?
Answer: 806
806-861Boiling Point: .lioiling point is defined as the temperature at which the vapour pressure of a liquid becomes equal to the atmospheric pressure or any external pressure". When a liquid is heated. its molecules gain energy. The number of molecules which have moo than average kinetic energy increases. More and more molecules becomes energetic enough u overcome the intermolecular forces. Due to this, rate of evaporation increases that results increase of vapour pressure until a stage reaches where the vapour pressure of a liquid become equal to atmospheric pressure. At this stage the liquid starts boiling
Question: 807
Why HCl has dipole-dipole forces of attraction?
Answer: 807
807-861HCl has dipole-dipole forces of attraction. The unequal sharing of electrons between two different types of atoms make one end of molecule slightly positive and other end slightly negatively charged. As shared pair of electron is drawn towards more electronegative atom, it is partially negatively charged. as chlorine in hydrogen chloride. 'The other end automatically becomes partially positively charged.
Question: 808
Why is BF3, electron deficient?
Answer: 808
808-861In BF3 molecule, three valence electrons of boron atom pair up with three electrons, one from each of three fluorine atoms. the boron atom even after the sharing of electron, remain shortage of 2 electrons in its outer most shell
Question: 809
Anode of downs cell is made up of non metal , what is its name ?
Answer: 809
809-861Anode of down cell is made of non-metal , Its name is graphite . The Cl- ions are oxidized to give Cl2 gas at anode
Question: 810
Why ionic compounds easily dissolve in water?
Answer: 810
810-861They dissolve easily in water because water is a polar solvent and has high dielectric constant that weakens the attraction between ions.
Question: 811
Why does group 1 elements prefer to combine with group 17 elements.
Answer: 811
811-861The elements of Group-1 being metals have the tendency to lose their valence electrons forming positively charged ions. Whereas non-metals of Group-17 have the tendency to gain or accept electrons. They are electronegative elements with high electron affinities. If atoms belonging to these two different group, metals and non-metals, are allowed to react. chemical bond is formed
Question: 812
Why the density of a gas is measured in gdm-3while that of a liquid is expressed in gcm-3?
Answer: 812
812-861The density of a gas is measured in gdm-3while that of a liquid is expressed in gcm-3because gases have large volume which is measured by large unit dm3while liquid has less volume so it is measured by small unit cm3
Question: 813
Write two physical properties of non-metals.
Answer: 813
813-8611: Non-metals have less melting and boiling point (except diamond)
2: They are generally soft (except diamond)
Question: 814
What type of elements have tendency of sharing of electrons?
Answer: 814
814-861If bond formation is between similar atoms or between the atoms that have comparable electronegativities. then the chemical bond formation is by sharing of electrons
Question: 815
Why chlorine can accept only 1 electron?
Answer: 815
815-861Chlorine has seven electrons in its valence shell. Chlorine being an electronegative element has the tendency to gain only one electron. They attain electronic configuration to the nearest noble gas "Ar"
Question: 816
Why does rate of diffusion increase with increase of temperature?
Answer: 816
816-861Diffusion increases by increasing temperature because at high temperature the in termolecular forces become weak due to high kinetic energy of the molecules
Question: 817
What types of electron pairs make a molecule good donor ?
Answer: 817
817-861The lone pair of electron make a molecule a good donor
Question: 818
Which type of electron are responsible for holding the atoms together in metals ?
Answer: 818
818-861Nuclei of metal atoms appear submerged in sea of these free mobile electrons . These mobile electrons are responsible for holding the atoms of metals together forming a metallic bond
Question: 819
Which electrons are involved in chemical bonding?
Answer: 819
819-861Only valence shell electrons are involved in chemical bonding
Question: 820
What type of attractive forces exist between HCL molecules ?
Answer: 820
820-861Dipole-dipole attractiveforces exist between HCL molecules.
Question: 821
Why suspension does not form homogeneous mixture?
Answer: 821
821-861sn, Particles remain un dissolved and from a heterogeneous mixture. Particles settle down after some times.
Question: 822
Define the term allotropy ?
Answer: 822
822-861Allotropy: The existence of an element in more than one forms in same physical state is called allotropy.
Question: 823
Why do the bigger size atoms have more shielding effect?
Answer: 823
823-861In bigger size atoms the number of inner shells and inner shell electrons increases hence the shielding effect in bigger size molecules also increases.
Question: 824
State Charles's law
Answer: 824
824-861The volume of a given mass of a gas is directly proportional to the absolute temperature when pressure kept constant."
Question: 825
Why the electrons move freely in metals ?
Answer: 825
825-861This is because the valence shell electrons loosely held by nucleus of an atom . There is the weak force of attraction present between nucleus and the mobile valence electrons . Therefore valence electrons move freely in metals
Question: 826
Differentiate between solute and solvent ?
Answer: 826
826-861Solute : The component which is present in smaller quantity is called solutee.g : Salt in water , salt is solute
Question: 827
Why gases are compressible ?
Answer: 827
827-861Gases are highly compressible due to empty spaces between their molecules . When the gases are compressed , then molecules come closer to one another and occupy less volume than in uncompressed state
Question: 828
In electroplating of silver, from where Ag+ ions come and where they deposit?
Answer: 828
828-861In electroplating of silver in the cell, the anode dissolves to produce Ag+ ions, that towards the cathode. At cathode they're discharged and deposited on the object e.g. spoon. chemical reaction can be represented as:
Question: 829
Is the Boyle's law valid at very high temperature?
Answer: 829
829-861No. Boyle's law is not valid at very high temperature
Question: 830
Why the rate of diffusion of gases is rapid than that of liquid ?
Answer: 830
830-861The rate of diffusion of gases is rapid than that of liquid because the movement of gas molecule is rapid as compared to liquid , So due to random motion and collision gases diffuses rapidly
Question: 831
When a gas is allowed to expand, what will be its effect on its temperature?
Answer: 831
831-861According to Charles' Law when gas is allowed to expand its temperature also increases.
Question: 832
What is transition temperature of sulphur?
Answer: 832
832-861Its transition temperature is 96℃.
Question: 833
Why does evaporation increase with the increase of temperature?
Answer: 833
833-861At high temperature, rate of evaporation is high because at high temperature kinetic energy of molecules increases. So, it is high that they over-come the intermolecular forces and evaporate rapidly. For example, water level in a container with hot water decreases earlier than that of a container with cold water.
Question: 834
Which is lighter one aluminium or gold?
Answer: 834
834-861Aluminum is lighter than gold because density or aluminium is 2.70 gcm'-3 While of gold is 9.3 gcm-3
Question: 835
Why suspensions and solutions do not show Tyndall effect , while colloids do ?
Answer: 835
835-861Suspensions and solutions do not show Tyndall effect because particles of solution are so small that can't be scatter the rays of light and particles of suspension are so big that light is blocked and difficult to pass . The colloids do show Tyndall effect because particles scatter the path of light rays thus emitting the beam of light i-e exhibit the Tyndall effect
Question: 836
Give chemical reaction between Methane (CH4) and chlorine (Cl2) in presence of diffused light .
Answer: 836
836-861CH4 + Cl2 ➜ CH3Cl +HCL
CH3Cl +Cl2 ➜ CH2Cl2+HCL
CH2Cl2 + Cl2 ➜ CHCl2 +HCL
CHCL3 + Cl2 ➜ CCl4 ➜ CCl4 +HCL
Question: 837
Why is melting point of a solid considered its 'identification' characteristics ?
Answer: 837
837-861The melting point of a solid considered its identification because pure solids have a sharp and specific melting point , no other solid has same melting point
Question: 838
Why amorphous solids do not have sharp melting points while crystalline solids do have ?
Answer: 838
838-861Amorphous means shapeless . Solids in which the particles are not regularly arranged or their regular shapes are destroyed are called amorphous solids . They do not have sharp melting points . While solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solids . They have definite surface or faces . Each face has definite angle with other . They have sharp melting points
Question: 839
Why is white tin available at room temperature?
Answer: 839
839-861White tin available at room temperature because it is stable at room temperature above 13.2°C
Question: 840
Define solution ?
Answer: 840
840-861A solution is homogenous mixture of two or more substances
Question: 841
Why we stir paint thoroughly before using?
Answer: 841
841-861We stir paints thoroughly before using because paints is suspension and suspension is heterogeneous mixture of un- dissolved particles which can be seen with naked eye and settle down alter sometime. We stir paints thoroughly so that particles suspend again
Question: 842
What are elements in group 3 to 12 called ?elements are normal elements because their valence electrons lie in s and p sub shell
Answer: 842
842-861Elements in group 3 to 12 elements are normal elements because their valence electrons lie in s and p sub shell
Question: 843
Classify the following into true solution and colloidal solution?
Answer: 843
843-861Blood, Starch solution, glucose, tooth paste, copper sulphate, silver nitrate solution. Blood. Starch solution. tooth paste are the colloidal solution. Glucose solution. copper sulphate solution and silver nitrate solution are true solution.
Question: 844
Which of the following will scatter light and why?
Sugar solution, Soap solution, Milk of magnesia.
Answer: 844
844-861Soap solution is colloidal solution and have particles large enough to scatter the light
Question: 845
In electroplating of chromium which salts is used as an electrolyte?
Answer: 845
845-861In electroplating of chromium, Cr2(SO4)3, is used as an electrolyte.
Question: 846
What is percentage-mass/mass(%m/m)?
Answer: 846
846-861It is the number of grams of solute in 100 grams of solution
Question: 847
Can colloids he separated by filtration, if not why?
Answer: 847
847-861Colloids cannot be separated by filtration because particles are big but they can pass through a filter paper.
Question: 848
What is the percentage m/volume ?
Answer: 848
848-861It is the number of grams of solute dissolved in 100cm3of solution
Question: 849
Define Electrochemistry.?
Answer: 849
849-861Electrochemistry is the branch of chemistry which deals with the relationship b-cl electricity and chemical reactions.
Question: 850
What characteristics properties do the covalent compound have ?
Answer: 850
850-861They have usually low melting and boiling points. (ii I Flicy are usually bad conductors of electricity. lit: I hey are usually insoluble in water. IR I Bigger molecules with three dimensional bonding form covalent crystals which are very stable and hard. They have high melting and boiling points.
Question: 851
What is redox reaction ?
Answer: 851
851-861The reaction in which simultaneously oxidation and reduction takes place is called redox reaction
Question: 852
Differentiate between oxidation and reduction.
Answer: 852
852-861Oxidation : Oxidation is defined as addition of oxygen or removal of hydrogen during a chemical reaction
e.g
ZnO + C➜Zn +CO2
Question: 853
Why dose ice float on water?
Answer: 853
853-861lCe float on water due to hydrogen bonding. The density of ice is 0.917gcm-3 at OT and of water is 1 gcm3 at 0°C. Due to this ice molecules expand and float on water
Question: 854
If repulsive forces dominate to attractive forces will a covalent bond form?
Answer: 854
854-861If the repulsive forces dominate to attractive forces the covalent will not be formed. The covalent bond formed only when the attractive forces dominates over the repulsive forces.
Question: 855
What is diffusion ? Explain with example ?
Answer: 855
855-861Diffusion is defined as spontaneous mixing up of molecules by random motion and collisions to form a homogeneous mixture
Question: 856
What is absolute temperature scale?
Answer: 856
856-861Lord Kelvin introduced absolute temperature scale or Kelvin scale • This scale of temperature starts from OK or -273.15°C which is given the name of absolute zero.
Question: 857
Convert the following. Ans: a) 70 cm lig to atm. b) 3.50atm to torr. c) 1.5 atm to Pa.
Answer: 857
857-86170 cm Hg to atm
We know that
76 cm 11g= 1 atm
1 em = 1/76 atm
70 cm Hg = 1/76. 70atm
70 cm lig =0.92 atm
Question: 858
Which allotropic form of carbon is stable at room temperature (25°C)?
Answer: 858
858-861Graphite is more stable at room temperature
Question: 859
How does nature of attractive forces of solute-solute solvent -solvent affect the solubility?
Answer: 859
859-861Solutions formation depends upon the relative strength of attractive forces between solute - solute , solvent-solvent and solute-solvent . Generally solutes are solids , ionic solids are arranged in such a regular pattern that the inter ionic forces are at a maximum . If the new forces between solute and solvent particles overcome the solute-solvent attractive forces , then solute dissolves and make a solution . If the forces between solute particles are strong enough then solute-solute forces , solute remains insoluble and solution is not formed
Question: 860
Name the by-products produced in Nelson's Cell?
Answer: 860
860-861The chlorine and hydrogen gas are produce as by product in Nelson's Cell
Question: 861
Difference between oxidation state and valency
Answer: 861
861-861Oxidation : Oxidation state is apparent charged assign to an atom of an element in a molecule or an ion .
While assigning O.S the sign precedes the number
e.g +2
