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Question: 1
What are the uses of Nuclear Chemistry?
Answer: 1
1-861It has vast application in medical treatment, preservation of food and generation of electrical power through nuclear reactors.
Question: 2
Define Empirical formula and give examples.
Answer: 2
2-861"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: 3
Define atomic mass unit. Why is it needed?
Answer: 3
3-861Atomic 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: 4
Give the composition of Earth Crust with respect to three major elements.
Answer: 4
4-861Earth Crust is formed by three major elements having following percentages.
Oxygen 47%
Silicon 28%
Aluminum 7.8%
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 Chemistry?
Answer: 6
6-861The Branches of Science which deals with the composition, structure, properties and reactions of matter is called chemistry.
Question: 7
On the basis of properties, elements are divided into which groups?
Answer: 7
7-861On the basis of properties elements are divided into metals, non-metal, and metalloids
Question: 8
Define Relative atomic mass?
Answer: 8
8-861"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: 9
What is the significance of the symbol of an elements?
Answer: 9
9-861Significance 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: 10
Define Industrial Chemistry and Analytical Chemistry.
Answer: 10
10-861Industrial 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: 11
What is the application of Inorganic Chemistry?
Answer: 11
11-861It has application in every aspect of chemical industry such as glass, cement, ceramics and metallurgy.
Question: 12
Why atomic mass of an atom is defined as relative atomic mass?
Answer: 12
12-861ATomic 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: 13
What are application of inorganic chemistry.
Answer: 13
13-861It has application is every aspect of chemical industry such as glass, cement, ceramics and metallurgy.
Question: 14
Name one solid, one liquid and one gaseous element present at room temperature?
Answer: 14
14-861Solid : Sodium, Iron
Liquid: Bromine and Mercury
Gas: Oxygen , Nitrogen, and Chlorine
Question: 15
Define empirical formula and give examples.
Answer: 15
15-861It is the simplest whole number , ratio of atoms present in a compound."
Empirical formula of benzene
Empirical formula of Hydrogen peroxide
Question: 16
What is meant by variable valency?
Answer: 16
16-861Some 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: 17
Which term is used to represent the mass of 1 mole of molecules of a substance?
Answer: 17
17-861Gram molecular mass
Question: 18
What is teh relationship between mass and mole of a substance?
Answer: 18
18-861The relationship between mass and mole of substance is given as following mass of substance = No of moles x Molar mass of substance
Question: 19
What is Radical?
Answer: 19
19-861An 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: 20
How many atoms are present in one gram atomic mass of a substance?
Answer: 20
20-861One gram atomic mass of a substance is equal to Avogadro's number in which 6.023 x 1023 atoms are present
Question: 21
How does homogenous mixture differ from heterogenous mixture ?
Answer: 21
21-861Homogenous mixture : Mixtures that have uniform composition through are called homogenous mixture
Question: 22
How many atoms are in I amu and I g of hydrogen .
Answer: 22
22-8611 amu and 1 gram of hydrogen has 6.022x1023 atoms.
Question: 23
Is atomic mass unit a SI unit of an atomic mass?
Answer: 23
23-861Yes , Atomic mass unit is SI unit of atomic mass.
Question: 24
What is valency?
Answer: 24
24-861The combining capacity of an element with other elements is called valency
For example. Valency of carbon is 4
Question: 25
Which one has more molecules : 9 g of water or 9 g of sugar C12 H22 O11 ?
Answer: 25
25-8619g of water has more molecules than 9 g of sugar because moles of water are more than sugar
For water
Question: 26
Define relative atomic mass .
Answer: 26
26-861Relative 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: 27
is the mass of 1 mole of Oxygen and 1 mole of Sulphur same.
Answer: 27
27-861No, the mass of 1 mole of oxygen and 1 mole of sulphur atom is not same.
Question: 28
How many atoms are present in 16 g of O and 8g of S?
Answer: 28
28-86116 grams of oxygen has 6.022 x 1023atoms and 8 grams of sulphur has 1.055x1023atoms.
Question: 29
Which one has more formula units : 1g of NaClor 1 g KCL ?
Answer: 29
29-861NaCl has more formula units than KCl
For NaCl
Formula unit = Mass / Formula mass
= 1/58.5
= 0.017
Question: 30
State three reasons why do you think air is a mixture and water a compound
Answer: 30
30-861Air (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: 31
Differentiate between homogenous and heterogenous mixture .
Answer: 31
31-861Homogenous Mixture : Mixtures that have have uniform composition throughout are calledhomogenous mixture
Question: 32
Define empirical formula and give example .
Answer: 32
32-861It is the simplest whole number , ratio of atoms present in a compound
Question: 33
How can you justify that air is a homogenous mixture . Identify substance present in it ?
Answer: 33
33-861Air 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: 34
What is atomic number, how it is represented?
Answer: 34
34-861"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: 35
What is the relationship between atomic number and atomic mass?
Answer: 35
35-861The 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: 36
Find out the mass of 3 moles of oxygen atoms.
Answer: 36
36-8613 x 16 = 48 g of oxygen are present in 3 moles.
Question: 37
Which of the following cases the number of hydrogen atoms is more?
Answer: 37
37-8611 mole of NH3 has more hydrogen atoms than 2 moles of HCL
Question: 38
What do you mean by 1 atom carbon and 1 gram atom of Carbon.
Answer: 38
38-861One 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: 39
Which branch of chemistry deals with preparation of paints and papers?
Answer: 39
39-861"Industrial chemistry deals with preparation of paints and papers."
Question: 40
What is the relationshp between atomic number and atomic mass?
Answer: 40
40-861The relation between atomic number and atomic mass is as following A = Z + n
Question: 41
What is the significance of chemical formula ?
Answer: 41
41-8611: It represents the name of the substance e.g H2O (water)
Question: 42
Explain why are oxygen and hydrogen considered elements whereas water as a compound ?
Answer: 42
42-861Hydrogen and oxygen are element because
1: Each one of it consists of same type of atoms
Question: 43
In which branch of chemistry deals with preparation of paints and papers?
Answer: 43
43-861"Industrial chemistry deals with preparation of paints and papers".
Question: 44
What is the relationship between empirical formula and formula unit.
Answer: 44
44-861All the organic compounds are represented by formula unit. Formula unit is also and empirical formula of Ionic compounds.
Question: 45
Difference between homogeneous and heterogeneous mixture.
Answer: 45
45-861Homogeneous mixture: Mixtures that have uniform composition throughout are called homogeneous mixtures.
example: Milm, Brass, Ice-cream.
Question: 46
Differentiate between homoatomic and heteroatomic molecules with examples .
Answer: 46
46-861Homoatomic molecules : A molecule containing same type of atoms is called homoatomic molecule
Question: 47
Define Biochemistry.
Answer: 47
47-861"It is branch of chemistry in which we study the structure, composition and chemical reactions of substances found in living organisms .
Question: 48
Differentiate between empirical and molecular formula.
Answer: 48
48-861Empirical formula: it is the simplest whole number ratio of atoms present in a compound
e.g. Empirical formula of benzene is CH.
Question: 49
Differentiate between molecule or molecular ion ?
Answer: 49
49-861Molecule :
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: 50
Which branch of chemistry deals with energy of atoms and its uses in daily life.
Answer: 50
50-861Nuclear chemistry deals with energy of atoms and its uses in daily life.
Question: 51
Define industrial chemistry and analytical chemistry
Answer: 51
51-861Industrial 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: 52
How many times is 1 mole of oxygen atom heavier than 1 mole of hydrogen atom?
Answer: 52
52-861One mole of oxygen atom is 16 times heavier than the one mole of hydrogen.
Question: 53
What elements do the following compound contains ?
Answer: 53
53-861Sugar ,common salt , lime water and chalk
Question: 54
Write down the chemical reactions of chlorine with hot and cold aqueous solutions of sodium hydroxides
Answer: 54
54-861Chlorine reacts with cold dilute NaOH to give sodium hypochlorite .
2NaOH +Cl2➜ NaCl+ NaOCL +H2O
Question: 55
Give the composition of milk.
Answer: 55
55-861Milk is a mixture of calcium , water, sugar, fat, proteins, minerals, salts and vitamins.
Question: 56
How many molecules of water are present in half mole of water ?
Answer: 56
56-861Water molecules in half moles = 1/2x6.02x1023
= 3.01x1023 molecules
Question: 57
How can you differentiate between organic and inorganic chemistry .
Answer: 57
57-861Organic chemistry : It is the study of the properties and behavior of hydrocarbons (compounds of carbon and hydrogen ) and their derivatives
Question: 58
Which branch of chemistry deals with the structure and properties of naturally occurring molecules.
Answer: 58
58-861"Organic chemistry deals with the structure and properties of naturally occuriring molecules."
Question: 59
In which branch of chemistry behaviour of gases and liquid is studied?
Answer: 59
59-861The behaviour of gases and liquids is studied in the branch of chemistry called physical chemistry.
Question: 60
What is free radical? Give example.
Answer: 60
60-861"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: 61
Write difference between physical and chemical properties .
Answer: 61
61-861Chemical 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: 62
Name one solid , one liquid and one gaseous element present at room temperature ?
Answer: 62
62-861Sodium ( Na) , Iron ( Fe)
Question: 63
Define atomic mass unit . Why is it needed ?
Answer: 63
63-861The unit for relative , atomic mass unit
Question: 64
Define chemistry ?
Answer: 64
64-861The branch of science which deals with the composition , structure , properties and reactions of matter is called chemistry .
Question: 65
What is radical
Answer: 65
65-861An 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: 66
Write chemical reaction of H2 with F2 and Cl2 .
Answer: 66
66-861Reaction of H2 with F2: Flourine combines with hydrogen even in the dark and cold state
H2 +F2➜ 2HF
Question: 67
How many atoms of sodium are present in 3 moles of sodium and what is the mass of it ?
Answer: 67
67-861Number of atoms of sodium are present in 3 moles = 3x6.02x1023 atoms
= 1.806x 1024
Question: 68
Write down chemical reaction of sodium with H2 and Cl2 .
Answer: 68
68-861Reaction of hydrogen with sodium :
Sodium reacts with hydrogen at high temperature to form hydrides
2 Na + H2➜ 2NaH
Question: 69
Give the scope of biochemistry .
Answer: 69
69-861It 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: 70
Write down the name of any two elements which were discovered in early ages .
Answer: 70
70-861Following elements were discovered in early ages
Question: 71
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: 71
71-8611:Zinc + Copper
It will be a mixture called a brass (alloy)
Question: 72
How many amu 1 g of a substance has ?
Answer: 72
72-8611.66x 10-24g +1 amu
1g = 1/1.66x 10-24amu
Question: 73
If 16 gram of oxygen contains 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams.
Answer: 73
73-86116 g of oxygen = 1 mole of oxygen
Mass of one atom of oxygen = 16 grams.
Question: 74
Differentiate between molecular mass and formula mas , which of the following is molecular formula ?
. H2O
.NaCl
.Kl
.H2SO4
Answer: 74
74-861Molecular mass :
The sum of atomic masses of all the atoms present in one molecule of a molecular compound is its molecular mass
Question: 75
Differentiate between ions and free radicals ?
Answer: 75
75-861Ions :
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: 76
In which branch of chemistry are the metabolic processes of carbohydrates and proteins studied ?
Answer: 76
76-861In biochemistry metabolic processes carbohydrates and proteins are studied
Question: 77
Define chemistry ? Explain two branches of chemistry .
Answer: 77
77-861Chemistry : The Branch of science which deals with the composition , structure, properties and reaction of matter is called chemistry
Question: 78
Differentiate between substance and mixture .
Answer: 78
78-861Substance : A piece of matter in pure form is termed as substance
e,g Glucose (C6H12O6 ) Oxygen
Question: 79
What is the atomic number , how it is represented ?
Answer: 79
79-861The atomic number of an element is equal to the number of protons present in the nucleus of its atoms
Question: 80
Which has more atoms :10g of Al or 10 g of Fe ?
Answer: 80
80-86110 g of A 1 has more atoms than 10 g of Fe
For A 1
Question: 81
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: 81
81-8612: Water + Sugar
It will be a solution or mixture called sugar syrup
Question: 82
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: 82
82-861Elements :
He , H2 ,Co, Gold , Iron
Question: 83
In the basis of properties , elements are divided into which group ?
Answer: 83
83-861On the basis of properties elements are divided into metals , non-metals and metalloids
Question: 84
State three reasons why do you thing soft drink is a mixture and water is a compound .
Answer: 84
84-861Soft drink is a mixture because :
1: Its components are not bounded chemically
2: The components do not have fix ratio
Question: 85
Which branch of chemistry deals with energy of atoms and its uses in daily life ?
Answer: 85
85-861Nuclear chemistry deals with energy of atoms and its uses in daily life
Question: 86
Which six elements constitute 99% of body mass and what are their percentages ?
Answer: 86
86-861Following six elements constitute 99%of body mass
Oxygen 65%
Hydrogen 10%
Calcium 1.5 %
Carbon 18%
Nitrogen 3%
Phosphorous 1.5%
Question: 87
How many atoms are in 1 amu and 1g of hydrogen (H)?
Answer: 87
87-8611amu and 1 gram of hydrogen (H) has 6.022x1023 atoms and 8 grams of sulphur has 1.005x1023atoms
Question: 88
How many atoms are present in 16g of Oand of S ?
Answer: 88
88-86116 grams of oxygen has 6.022x1023atoms and 8 grams of sulphur has 1.055x1023 atoms
Question: 89
Write down the electronic configuration of Al3+. How many electrons are present in its outer most shells
Answer: 89
89-861Al3+ = 1s2 ,2s2 ,2p6
Question: 90
Differentiate between empirical and molecular formula .
Answer: 90
90-861Empirical formula: It is the simplest whole number ratio of atoms present in a compound
Question: 91
Give the composition of milk .
Answer: 91
91-861Milk is a mixture of calcium , water ,sugar , fat , proteins , minerals, salts , and vitamins
Question: 92
What is the relationship between atomic number and atomic mass ?
Answer: 92
92-861The 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: 93
What are the uses of nuclear chemistry ?
Answer: 93
93-861It has vast application in medical treatment , preservation of food , and generation of electrical power nuclear reactors
Question: 94
Give the composition of earth crust with respect to three major elements .
Answer: 94
94-861Earth crust is formed by three major elements having following percentages
Question: 95
What are applications of inorganic chemistry?
Answer: 95
95-861It has application in every aspect of chemical industry such as glass , cement , ceramics and metallurgy
Question: 96
What is valency ?
Answer: 96
96-861The combining capacity of an element with other element is called valency
Question: 97
Define industrial chemistry and analytical chemistry ?
Answer: 97
97-861Industrial chemistry : It is the branch of chemistry that deals with the manufacturing of chemical compounds on commercial scale
Question: 98
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: 98
98-861a: There are two electrons in outermost shell
b : In sub-shell of outermost shell electron are present
1s2 , 2s2 , 2p6 .3s2
Question: 99
What is meant by variable valency ?
Answer: 99
99-861Some elements show more than one combining power (valency) that is called variable valency
Question: 100
Which branch of chemistry deals with the structure and properties of naturally occurring molecules ?
Answer: 100
100-861Organic chemistry deals with the structure and properties of naturally occurring molecules
Question: 101
What is meant by element ? Explain with example .
Answer: 101
101-861Element 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: 102
What is the relationship between empirical formula and formula unit ?
Answer: 102
102-861All the ionic compounds are represented by formula unit . Formula unit is also and empirical formula of ionic compounds
Question: 103
Write name of any two elements found in gaseous state
Answer: 103
103-861Nitrogen and oxygen both found in gaseous state
Question: 104
What observations were the observations made by Rutherford ?
Answer: 104
104-861There were two observations .
Question: 105
What is radical ?
Answer: 105
105-861An 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: 106
Find out molecular mass and formula masses of the following
Na2SO4 ,ZnSO4 , and CuCO3.
Answer: 106
106-861Formula mass of Na2SO4 = 2(23)+32+4 (16)
= 46+32+64
=142 amu
=142 amu
Question: 107
Explain difference between physical chemistry and biochemistry .
Answer: 107
107-861Physical 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: 108
What is matter ?
Answer: 108
108-861Anything which has mass and occupy space is called matter
Question: 109
Is atomic mass unit a SI unit of an atomic mass ?
Answer: 109
109-861Yes ,atomic mass unit is SI unit of atomic mass
Question: 110
Differentiate between atom and ion ?
Answer: 110
110-861Atom :
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: 111
How many atoms are present in one gram atomic mass of a substance ?
Answer: 111
111-861One gram atomic mass of a substance is equal to Avogadro's number in which 6.023x1023atoms are present
Question: 112
Define organic chemistry and which industries covered by it
Answer: 112
112-861Organic chemistry : it is the study of covalent compounds of carbon and hydrogen and its derivatives
Question: 113
Is the mass of 1 mole of O and 1 mole of S same ?
Answer: 113
113-861Nothe mass of 1 mole of O and 1 mole of S is not same
Question: 114
How was it shown that atomic nuclei are positively charged ?
Answer: 114
114-861The 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: 115
What is the relationship between mass and mole of a substance ?
Answer: 115
115-861the relationship between mass and mole of a substance is given as following
Question: 116
Write any two applications of inorganic chemistry.
Answer: 116
116-861Inorganic chemistry has applications in following aspects of the chemistry industry
Question: 117
What will be the nature of charge on an atom when it loses an electron or when it gains an electron ?
Answer: 117
117-861When it lose an electron it become positive an when it gains and electron it become negative
Question: 118
For what purpose U-235 is used ?
Answer: 118
118-861When U-235 is bombarded with slow moving neutrons , uranium nucleus breaks up to produce Barium-139 and Krypton -94 and three neutrons
Question: 119
Find out the mass of 3 moles of oxygen atoms .
Answer: 119
119-8613x16 = 48g of oxygen are present in 3 moles
Question: 120
How many electrons will be in M-shell of an atom having atomic number 15 ?
Answer: 120
120-861K L M
2 8 5
5 electrons are present in M shell of an atom having atomic number 15
Question: 121
How many times is 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams
Answer: 121
121-861One mole of oxygen atom is 16 times heavier than the one mole of hydrogen
Question: 122
Define matter and mixture .
Answer: 122
122-861Matter : anything that has mass and occupies space is called matter . Matter exists in three physical states , solid , liquid , gas
Question: 123
Which term is used to represent the mass of 1 mole of molecules of a substance ?
Answer: 123
123-861Gram molecular mass
Question: 124
Why atomic mass of an atom is defined as relative atomic mass ?
Answer: 124
124-861Atomic 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: 125
Identify the following as empirical or molecular formula :
H2O2 ,CH4 , C6H12O6 , C12H22O11 ,BaCO3 ,KBr
Answer: 125
125-861Empirical formula : KBr , BaCO3 , CH4
Question: 126
In which branch of chemistry behaviour of gases and liquid is studied ?
Answer: 126
126-861The bahaviour of gases and liquid is studied in the branch of chemistry called physical chemistry
Question: 127
What is the empirical formula of acetic acid (CH3COOH)? Also calculate the molecular mass of acetic acid .
Answer: 127
127-861Empirical formula of acetic acid is CH2O
Question: 128
Differentiate between nuclear chemistry and environmental chemistry .
Answer: 128
128-861Environmental 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: 129
Define Biochemistry ? Describe scope of biochemistry and give two examples of biochemistry.
Answer: 129
129-861The branch of science concerned with the chemical and physico-chemical processes and substances that occur within living organisms.
Question: 130
Write any two elements found in the liquid state at room temperature .
Answer: 130
130-861Mercury and bromine are two elements found in the liquid state at room temperature
Question: 131
What is atomic number of phosphorous ? Write down its electronic configuration .
Answer: 131
131-861Atomic number of phosphorous (P) is 15
Electronic configuration
1s2 , 2s2 ,2p6 ,3s2 ,3p3
Question: 132
Differntiate between biochemistry and industrial chemistry .
Answer: 132
132-861Biochemistry : Biochemistry is the branch of chemistry in which w study the structure , composition , and chemical reaction of substances found in living organisms
Question: 133
Define biochemistry ?
Answer: 133
133-861It 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: 134
How was it is proved that whole mass of an atom is located at its center ?
Answer: 134
134-861The complete rebounce of a few particles show that the nucleus is very hard , dense and contain all mass of an atom
Question: 135
Name the particle which determine the mass of an atom ?
Answer: 135
135-861Protons and neutrons determine the mass of an atom
Question: 136
What is the nature of charge on cathode rays ?
Answer: 136
136-861Their deflection in electric and magnetic field proves that they have negative charge
Question: 137
Which branch of chemistry deals with preparation of paints and papers ?
Answer: 137
137-861Industrial chemistry deals with preparation of paints and papers .
Question: 138
If an element has atomic number 13 and atomic mass 27 , how many electrons are there in each atom of the element?
Answer: 138
138-861Atomic 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: 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
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: 140
140-861Proton = 15
Electron = 18
Neutron = 16
b: Phosphorous ion
c: E.C =1s2 , 2s2 , 2p6 , 3s2 ,3p6
Question: 141
Write down any two properties of metals .
Answer: 141
141-8611: They show metallic luster
Question: 142
Why does 10 g nitrogen gas contain the same number of molecules as 10g of carbon monoxide ?
Answer: 142
142-861Number of moles of nitrogen gas = 10/28 =0.35mol
Number of molecules of N2 = 0.35x0.22x1023
=2.107x1023
Question: 143
What do you mean by 1 atom of C and 1 gram of atom of C ?
Answer: 143
143-861One 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: 144
Why do the isotopes of an element have different atomic number masses?
Answer: 144
144-861As 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: 145
What is difference between elements and compound ?
Answer: 145
145-861Compound : Compound is a substance made up of two or more elements chemically combined together in a fixed ratio by mass
Example : Water (H2O)
Question: 146
What is meant by relative molecular mass?
Answer: 146
146-861Relative 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: 147
A patient has goiter . How will it be detected ?
Answer: 147
147-861The 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: 148
What is relative atomic mass ? How is it related to gram ?
Answer: 148
148-861The 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: 149
Name the elements represented by the following symbols W, Ba , Hg and Na
Answer: 149
149-861Tungsten W , Barium B , Mercury Hg , Sodium Na
Question: 150
Differentiate shell and sub-shell with example of each ?
Answer: 150
150-861Shell (Orbit):
The circular orbits of specific energy are called shells or energy levels
Question: 151
Why metals are good conductor of electricity ?
Answer: 151
151-861Metals are good conductors of heat and electricity in solid and liquid state due to mobile electrons
Question: 152
Why shielding effect of electron makes action formation easy ?
Answer: 152
152-861As 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: 153
What is meant by mixture ? Give example.
Answer: 153
153-861When two or more elements or compounds mix up physically without any fixed ratio they form a mixture
Question: 154
Define pressure and write its unit .
Answer: 154
154-861Pressure : It is defined as the force exerted by per unit surface area
Question: 155
If 16g of oxygen contains 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams
Answer: 155
155-86116g of oxygen =1 mol of oxygen
Mass of one atom of oxygen = 16 grams
Question: 156
Give electronic configuration of hydrogen ?
Answer: 156
156-861Electronic configuration of 11H is 1s1
Question: 157
Write down chemical formula of calcium phosphate and sodium chloride ..
Answer: 157
157-861Chemical formula of calcium phosphate and sodium chloride is as fellows :
Question: 158
Define isotope ?
Answer: 158
158-861Isotopes are defined as the atoms of elements that have same atomic number but different mass number
Question: 159
What is the significance of the symbol of an element ?
Answer: 159
159-861Symbol 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: 160
What is kept constant in Charles law ?
Answer: 160
160-861Pressure is kept constant in Charles law
Question: 161
Write two significance of chemical formula .
Answer: 161
161-8611: it indicates the mass of the compound in amu or grams
Question: 162
From which word atom derived ?
Answer: 162
162-861Atom is derived from latin word 'Atomos' meaning indivisible
Question: 163
What is meant by condensation ?
Answer: 163
163-861The returns of the vapours into liquids state on cooling is called condensation
Question: 164
How is periodicity of properties dependent upon the numbers of protons in an atom ?
Answer: 164
164-861In 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: 165
An element has an atomic number 17 , how many electrons are present in K and M shells of an atom ?
Answer: 165
165-861K=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: 166
What is difference between cation and anion ?
Answer: 166
166-861Cation: An atom or group of atoms having positive charge on it is called cation
Example : like Na , k
Question: 167
Why volume of gas decreases with increase of pressure ?
Answer: 167
167-861Volume 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: 168
What was the pressure inside the discharge tube in discovery of electron?
Answer: 168
168-861The pressure inside the tube was kept 10-4 atm
Question: 169
Why atomic number is more fundamental property to arrange elements than atomic mass?
Answer: 169
169-861Due to two reasons :
1: It increase regularly from element to element
Question: 170
Differentiate between molecular mass and formula mass .
Answer: 170
170-861Formula 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: 171
Give few properties of cathode rays .
Answer: 171
171-861a: These rays travel in a straight line perpendicular to the cathode surface
Question: 172
When do electrons emit or absorb energy ?
Answer: 172
172-861A 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: 173
What is free radical ? Give example.
Answer: 173
173-861Free radical : Free radical are atoms or groups of atoms possessing odd number (unpaired ) electrons.
Question: 174
Do you know any element having no neutron in its atom ?
Answer: 174
174-861Isotope of hydrogen , protium have one proton and no neutrons in it
Question: 175
Convert -45°C to kelvin temperature .
Answer: 175
175-861(T)K = (T)°C +273
(T)K = (-45)°C +273
(T)K = (-45+ 273)°C
(T)K = 228
Question: 176
If 16g of oxygen contains 1 mole of oxygen atom, calculate the mass of one atom of oxygen in grams .
Answer: 176
176-861No of atoms in one mole =6.02×1023
Question: 177
Give one example each of the use of radioactive isotope in medicine and radiotherapy ?
Answer: 177
177-861Radioactive isotopes is used in medicine
Iodine 131
Radioactive isotopes used in radiotherapy
P-32
Sr-90
Co-60
Question: 178
Write two properties of crystalline solids .
Answer: 178
178-8611: In crystalline solids particles are arranged in definite in definite pattern .
Question: 179
What isAvogadro's number?
Answer: 179
179-861Avogadro, 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: 180
Explain plum pudding theory .
Answer: 180
180-861Thomson 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: 181
Write short note on discovery of Neutron.
Answer: 181
181-861Chadwick 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: 182
What is vapour pressure ?
Answer: 182
182-861The pressure exerted by the vapour of a liquid at equilibrium with the liquid at a particular temperature is called vapour pressure of liquid
Question: 183
How many atoms of hydrogen present in 1 mole of water ?
Answer: 183
183-8611 mole of water = 6.02 x 1023molecules
1 mole of water has H atom =1x 6.02x1023atoms
= 6.02 x 1023
Question: 184
Define element?
Answer: 184
184-861Sodium (Na) and Hydrogen (H) etc
Question: 185
What is the capacity of shells ?
Answer: 185
185-861The number of electrons accommodated by the shell called capacity of shell
Question: 186
What is meant by molecular ion ?
Answer: 186
186-861When a molecule loses or gains one or more electron , it forms a molecular ion
Question: 187
Write two properties of ionic compound .
Answer: 187
187-8611: Ionic compound are mostly crystalline solid
Question: 188
What are blocks ? How many blocks are present in periodic table ?
Answer: 188
188-861On 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: 189
Define ionic bond and ionic compounds .
Answer: 189
189-861Ionic bond : The type of chemical bond which is formed due to complete transfer of electron from one another is called ionic bond
Question: 190
What was the thickness of gild foil used in Rutherford's atomic model ?
Answer: 190
190-8610.00004 cm thick gold foil was used by Rutherford in his experiment
Question: 191
Calculate the number of mole carbon in 84 gram of carbon .
Answer: 191
191-861 Mass of C = 84 gm
Molecular mass of C = 12 gm
Quantity of moles = 84/12
= 7 moles
Question: 192
What is meant by malleability ?
Answer: 192
192-861Malleabilityis the property by virtue of which a metal can be drawn into sheets
Question: 193
Define electronic configuration ?
Answer: 193
193-861Electronic configuration : The distribution of electrons around the nucleus in various shells and sub-shells according to increasing energy , is called electronic configuration
Question: 194
Which are physical properties of matter ?
Answer: 194
194-8611: Matter exists in three physical state i-e gas, liquid , and solid
Question: 195
Write four examples of mixture .
Answer: 195
195-8611: Air is a mixture of nitrogen , carbon dioxide , noble gasses and water vapours
Question: 196
Define atom according to Dalton ?
Answer: 196
196-861Atom is an indivisible , hard ,dense and sphere
Question: 197
How many electrons are present in sub-shell ?
Answer: 197
197-861s can have 2 electrons
p can have 6 electrons
d can have 10 electrons
f can have 14 electrons
Question: 198
Define Crystalline solids and give two examples .
Answer: 198
198-861Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solids
Question: 199
What is difference between compound and mixture / Give example .
Answer: 199
199-861Compound :
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: 200
An element has 5 electrons in M shell . Find its atomic number
Answer: 200
200-861The element has 5 electrons in M shell has atomic number 15 and name of element is phosphorous
Question: 201
Write properties of Neutrons .
Answer: 201
201-861Properties of neutrons particles are given below :
Question: 202
Give few properties of canal rays .
Answer: 202
202-861a: Deflection of these rays in electric and magnetic field proved that these were positively charged
Question: 203
How many neutrons are present in C-12 and C-13 ?
Answer: 203
203-861C-12 C-13
P=6 P=6
N=12-6=6 N=13-6=7
Question: 204
Write down the chemical formulas of the following
(a) Sugar (b) Sulphuric acid
Answer: 204
204-861(a) Sugar : C12H22O11
Question: 205
A long as electron remains in an orbit , it does not emit or absorb energy , when does it emit or absorb energy ?
Answer: 205
205-861When 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: 206
Who discovered proton , electron , neutron ?
Answer: 206
206-861In 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: 207
Define chemical formula and give one examples .
Answer: 207
207-861Definition : A chemical formula is the symbolic representation the elements in the compounds and the ratio of the elements to one another
Question: 208
Write down the number and names of subshell in N-shell .
Answer: 208
208-861Number of sub shell in N shell is 4 named as s ,p ,d and f
Question: 209
How many sub-shells are there in second shells ?
Answer: 209
209-861Two sub-shells s and p are present in second shell L
Question: 210
What is the difference between Mendeleev's and modern periodic law ?
Answer: 210
210-861Mendeleev's periodic law :
Properties of the element are periodic function of their atomic masses is called Mendeleev's periodic law
Question: 211
What is classical theory of radiation . How it is differ from quantum theory ?
Answer: 211
211-861According 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: 212
Define symbol and valency with example .
Answer: 212
212-861Symbol : The representation of any element with one or two english letters is called symbol.
Question: 213
How can you prove that angular momentum is quantized ?
Answer: 213
213-861mvr =nh/2π
The angular momentum of first orbit is (n=1)
mvr = 6.63x10-34/2x 3.14
Question: 214
Calculate no of carbon atoms in one mole C6 H12 O6
Answer: 214
214-8616 atoms of carbon are present in one mole of glucose
Question: 215
Convert 560 torr into cmHg
Answer: 215
215-8611 torr = 1mm Hg
Question: 216
Why and how are element arranged in 4th period ?
Answer: 216
216-861Elements 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: 217
What is the capacity of the K,L,M,N shells ?
Answer: 217
217-861K shell can accommodate 2 electron
L shell can accommodate 8 electrons
M shell can accommodate 18 electrons
N shell accommodate 32 electrons
Question: 218
What is quantum ?
Answer: 218
218-861Quantum means fixed energy . It is the smallest amount of energy that can be emitted or absorbed as electromagnetic radiation
Question: 219
What are shells ?
Answer: 219
219-861Shells are specific energy levels around nucleus in which electron resolve
e.g K,L,M,N
Question: 220
Why does an electron fill 2p orbital and then 3s and then 3s orbital ?
Answer: 220
220-861As 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: 221
Calculate the formulas mass of potassium sulphate
Answer: 221
221-861Formulas mass of potassium sulphate (K2SO4)
K2SO4 = 2(39)+(32)+4(16)
= 78+32+64
= 174a.m.u
Question: 222
Write two properties of covalent compounds
Answer: 222
222-8611: They have usually low melting and boiling points
Question: 223
What id meant by atom and ion?
Answer: 223
223-861Atom
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: 224
How many elements are in 3rd period, write their names and symbols?
Answer: 224
224-861There are eight elements in 3' period, sodium(Na), magnesium(Mg) .aluminium (AI).silicon(Si),phosphorus(P),sulphur(S),chlorine(Cl),argon(Ar)
Question: 225
What is mean by cation and anion? Explain with example.
Answer: 225
225-861Cation: 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: 226
Define nuclear fission reaction .
Answer: 226
226-861A reaction in which heavy nuclear splits up into two nuclei by absorbing show moving next ions
Question: 227
How many elements are in first period and what are their names and symbols?
Answer: 227
227-861There are two elements in first period, hydrogen (H), helium(He)
Question: 228
What is the valency id following ?
(A) Barium (B) Nitrogen (C) Sodium (D) Sulphur
Answer: 228
228-861Elements valency
1: Barium 2
2: Nitrogen 3
3: Sodium 1
4: Sulphur 2
Question: 229
Define pascal .It is the unit of which quantity ?
Answer: 229
229-861If one newton force is applied on 1m2area then pressure is called one pascal . It is unit of pressure
Question: 230
Explain how anode rays are formed from the gas taken in the discharge tube .
Answer: 230
230-861Anode 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: 231
Convert 30°Cto kelvin temperature
Answer: 231
231-861We 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: 232
Difference between molecular mass and formula mass.
Answer: 232
232-861Molecular Mass:
The sum of the atomic mass of all the elements present in a molecule is called as Molecular Mass.
Question: 233
How is the goiter in thyroid gland detected ?
Answer: 233
233-861Iodine -131 is used fir the diagnosis of goiter in thyroid gland
Question: 234
Which carbon isotope use in carbon dating ?
Answer: 234
234-861C-14 used in carbon dating
Question: 235
For an element Z = 92 A = 238 Calculate number of neutron in it
Answer: 235
235-861Atomic mass = No of protons + No of neutrons =A=238
No of protons Z = 92
No of neutrons =N=A-z
=238-92= 146
Question: 236
Why the bond between an electropositive and electronegative atom is ionic in nature ?
Answer: 236
236-861Electropositive elements lose electrons while electronegative elements gain electrons . That's why both combine and forms ionic bond
Question: 237
Calculate molecular mass of NH3.
Answer: 237
237-861Molecular mass :
NH3 =14+1*3
=17a.m.u
Question: 238
Define relative atomicmass based on C-12 scale.
Answer: 238
238-861Relative 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: 239
Electronic configuration of Cl- ion
Answer: 239
239-861Cl-1s2 ,2s2,2p6 ,3s2 ,3p6
Question: 240
Write any two properties of covalent compounds .
Answer: 240
240-8611: 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: 241
How does homogeneousmixture differ from heterogeneous mixture?
Answer: 241
241-861The mixture that has uniform composition throughout is called homogeneous mixture which composition is not uniform throughout e.g. soil , rock and wood etc.
Question: 242
On which two factors vapour pressure of any liquid depends ?
Answer: 242
242-861Vapour pressure of liquid depends upon following factors :
Question: 243
Why shielding effect of electrons makes action formation easy ?
Answer: 243
243-861As 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: 244
Write formulas of two ionic compounds which are soluble in water .
Answer: 244
244-861The two ionic compound which are soluble in water are following
Question: 245
Human body made up of how many elements ? Write their names .
Answer: 245
245-861Six 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: 246
Define atomic number and atomic mass .
Answer: 246
246-861Atomic 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: 247
Ionic compounds are solids. Explain
Answer: 247
247-861Ionic 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: 248
What are meant by coordinate covalent compounds ?
Answer: 248
248-8611: 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: 249
Write two difference between molecule and molecular ions .
Answer: 249
249-861Molecule :
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: 250
What is difference between solute and solvent ?
Answer: 250
250-861Solute : The component of the solution which is present in smaller quantity is called solute
Question: 251
Which gasses are present in air ? Write their names .
Answer: 251
251-861Oxygen , nitrogen , carbon dioxide , argon are major gasses present in air
Question: 252
Give some examples of arsenic and silver .
Answer: 252
252-861Symbols of arsenic and silver are as following
Question: 253
Define atomic mass unit .
Answer: 253
253-861One 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: 254
Differentiate between lone pair and bond pair of electron.
Answer: 254
254-861Lone 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: 255
In which unit body temperature is measured ?
Answer: 255
255-861Body temperature is measured in fahrenheit scale
Question: 256
What are Lanthanide and actinide series ?
Answer: 256
256-861Due to space problem two series of elements are placed below periodic table
Question: 257
Why cesium (At.No.55 ) requires little energy to release its one electron present in their outermost shell ?
Answer: 257
257-861Cesium 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: 258
Describe atIeast two necessary conditions for the formation of a covalent bond.
Answer: 258
258-861Iwo 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: 259
Define relative atomic mass.
Answer: 259
259-861Relative 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: 260
Why melting point and boiling points of ionic compounds are high?
Answer: 260
260-861Melting 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: 261
What do you mean by group or median in periodic table ?
Answer: 261
261-861The horizontal rows in periodic table called periods and vertical columns in the periodic table are called groups
Question: 262
Define effusion . Give example .
Answer: 262
262-861Effusion : Effusion is defined as the escaping of gas molecules through tiny holes into a space with lesser pressure
Question: 263
What would be the number of moles in 9.0 gram carbon ?
Answer: 263
263-861Number of moles of carbon = 9 g
Molar mass of carbon = 12 g
Number of moles = ?
Question: 264
An element has 5 electron in M shell . Find out its atomic number ?
Answer: 264
264-861The number of this element will be 15
Question: 265
Why cesium requires little energy to release its one electron present in the their outermost shell ?
Answer: 265
265-861Cesium 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: 266
Ionic bond is stronger than covalent bond . Explain .
Answer: 266
266-861Ionic bond formed between two opposite charges and electrostatic forces . That's why ionic compound is stronger than covalent bond
Question: 267
Why ionic compounds are easy soluble in water?
Answer: 267
267-861Water 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: 268
Difference between true solution and colloid solution?
Answer: 268
268-861True solution:Solutions are the homogeneous mixture of two or more than two components.
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
Why the rate of diffusion gases is rapid than that of liquids ?
Answer: 270
270-861The 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: 271
What is the difference between diffusion and effusion ?
Answer: 271
271-861Diffusion: The spontaneous mixing of molecules by random motion and collision of gases form homogenous mixture is called diffusion
Question: 272
Write chemical formula of Aluminium sulphate and Calcium phosphate .
Answer: 272
272-861Aluminium sulphate: Al2(SO4)
Question: 273
Define allotropy and give examples .
Answer: 273
273-861The existence of an element in more than one form in same physical state but different chemical properties is called allotropy .
Question: 274
How free radical is formed ?
Answer: 274
274-861Free radicals are formed by the homolytic (equal) breakage of bond between two atoms when they absorb heat or light energy
Question: 275
Define standard atmosphere pressure and write its unit .
Answer: 275
275-861The pressure exerted by a mercury column of 760mm at sea level called standard atmospheric pressure
Question: 276
Define homogenous mixture and give example .
Answer: 276
276-861Homogenous mixture: The mixture having uniform composition is calledhomogenous mixture
Question: 277
Write electronic configuration of Sulphur .
Answer: 277
277-861Electronic configuration of Sulphur :
Question: 278
What is diffusion ? Explain with example .
Answer: 278
278-861Diffusion : 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: 279
Define molecular mass and give example .
Answer: 279
279-861Molecular formula that shows actual number of atoms of each element present in molecules of that compound
Question: 280
Write the percentage of volume by weight of oxygen in atmosphere and oceans
Answer: 280
280-861In atmosphere oxygen is 21% while in oceans it is 86%
Question: 281
What is matter ? How many states it has ?
Answer: 281
281-861Matter is any thing that has mass and occupies space .
Question: 282
How does electron differ from a neutron ?
Answer: 282
282-861Electron
1: Electrons have negative charge
2: The mass of the electron is 1940 times less than proton
Question: 283
Write chemical formula of caustic soda and washing soda .
Answer: 283
283-861Caustic soda: NaOH
Question: 284
Write down the names of elements of groups 1 with their symbols .
Answer: 284
284-8611st 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: 285
Write electronic configuration of Aluminuim .
Answer: 285
285-861Atomic number of Aluminium is 13
13Al = 1s2 , 2s2, 2p6, 3s2, 3p1
Question: 286
Write two properties of gases
Answer: 286
286-8611: Molecules of gases are always in state of continuous motion . They have very high K.E .
Question: 287
Why densities of gases are less than liquids ?
Answer: 287
287-861Gases 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: 288
Write the chemical formula of water and sugar.
Answer: 288
288-861Water :C12H22O11
Question: 289
Differentiate between shell and sub shell and give example .
Answer: 289
289-861Sub 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: 290
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: 290
290-861Using the relationship :
Question: 291
Soft drink is a mixture while water is compound . Give the reason .
Answer: 291
291-861Water : Water forms by the chemical reaction of hydrogen and oxygen . that's why it is called compound
Question: 292
Calculate the gram molecule in 40g of phosphoric acid
Answer: 292
292-861Molar mass of phosphoric acid H3PO4 = 3+31+64=98
Question: 293
What is absolute temperature scale ?
Answer: 293
293-861Lord 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: 294
An element with A = 39 , Z = 19 .Calculate the number of electrons and protons in one atom of this element
Answer: 294
294-861Atomic 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: 295
Is the Boyle's law applicable to liquid ? Give reason .
Answer: 295
295-861No 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: 296
Define evaporation and give example ?
Answer: 296
296-861Evaporation: The conversion of liquid into vapours called evaporation .
Question: 297
What is charles law ? Write its equation .
Answer: 297
297-861French 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: 298
Why does sodium lose one electron and attain +1 charge?
Answer: 298
298-861Sodium 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: 299
What is relationship between Empirical formula and Molecular formula ?
Answer: 299
299-861The relationship between Empirical formula and Molecular formulais given as
Molecular formula = (Empirical formula)*n
When n = 1,2 ,3 and so on
Question: 300
What is the reason of arranging elements in a group?
Answer: 300
300-861The reason of arranging of elements in a groups, is that they have same electronic configuration and same properties so they form a family.
Question: 301
Write the name of two non-polar solvents .
Answer: 301
301-861Toluene and benzene aretwo non-polar solvents
Question: 302
What is the empirical formula of acetic acid ? Calculate its molecular mass.
Answer: 302
302-861Empirical formula of acetic acid CH2O
Question: 303
Write the names of two allotropic forms of sulphur .
Answer: 303
303-861The allotropic forms of sulphur are given below :
Question: 304
Calculate the molecular mass of the carbon dioxide .
Answer: 304
304-861Molecular mass of the carbon dioxide
CO2 = 12+2 (16)
= 44amu
Question: 305
Define empirical formula and give an examples .
Answer: 305
305-861Empirical formula: empirical formula is a formula which represents the simplest whole number ratio of atoms present in a compound
Question: 306
What are two factors on which evaporation depends ?
Answer: 306
306-861Surface area : Evaporation is a surface phenomenon . Greater is surface area greater is evaporation
Question: 307
How is periodicity of properties dependent upon the number of protons in an atom ?
Answer: 307
307-861In 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: 308
What is ionic bond? Give an example.
Answer: 308
308-861Definition: A chemical bond which is formed due to complete transfer of electron from one atom to another atom is called ionic bond.
Question: 309
Why does evaporation increases with the increase in temperature ?
Answer: 309
309-861Evaporation 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: 310
Write down the name of particles which determine the mass of an electron .
Answer: 310
310-861The proton and neutron determine the mass of an atom
Question: 311
Why does evaporation cause cooling ?
Answer: 311
311-861When 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: 312
Define groups ?
Answer: 312
312-861The vertical columns in periodic table are called groups . Numbered from 1 to 18
Question: 313
Briefly describe the mobility of gases.
Answer: 313
313-861Gas 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: 314
Why the size of atom does not decrease regularly in periods ?
Answer: 314
314-861The atomic size does not decrease regularly in periods due to presence of transition elements . The size of atom first decreases then increases
Question: 315
How cation and anion is formed ?
Answer: 315
315-861Cation is formed by the loss of one or more electrons
Question: 316
Write difference between saturated solution and unsaturated solution .
Answer: 316
316-861Saturated solution : The solution containing maximum amount of solute at a given temperature is called saturated solution
Question: 317
What is maximum capacity of a metal ?
Answer: 317
317-8611: K shall can accommodate 2 electrons
Question: 318
Why is naphthalene soluble in carbon tetrachloride and not in water ?
Answer: 318
318-861Non -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: 319
What is meant by ion ? Give example .
Answer: 319
319-861Ion is an atom or group of atoms having a charge on it .
Question: 320
Write two difference between atom and anion
Answer: 320
320-861Ion :
1: It is the simplest unit of ionic compound
2: It has net charge either negative or positive on it
Question: 321
Whether the density of gases increase on cooling ?
Answer: 321
321-861The density of gases increasing by cooling because their volume decreases and molecules of gases came close to each other
Question: 322
Why the elements are called s and p block elements?
Answer: 322
322-861The elements having their valence electrons in s and p sub shell called s and p blocks elements.
Question: 323
Define Triatomic molecule and polyatomic molecule
Answer: 323
323-861Polyatomic molecule : The molecules which consists of many atoms calledpolyatomic molecule
Question: 324
Why benzene is insoluble in water ?
Answer: 324
324-861The 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: 325
Why HCl has dipole-dipole forces of attraction?
Answer: 325
325-861HCl 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: 326
Explain any two factors that effect the diffusion .
Answer: 326
326-861Factors effecting in diffusion :
1 :Size of molecules : Big sized molecules diffuse slowly
Question: 327
What are the defects of Mendeleev's periodic table or why improvement was make in Mendeleev's periodic table?
Answer: 327
327-861There are two defects in Mendeleev's periodic table:
Question: 328
Write two properties of liquid state of matter
Answer: 328
328-8611: Liquid have fixed volume but no fixed shape . It attains the shape of container in which it is kept
Question: 329
What is compressibility?
Answer: 329
329-861Decrease 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: 330
Write down the chemical formula of silicon dioxide and calcium chloride .
Answer: 330
330-861Silicon dioxide SiO2
Question: 331
How will you test weather given solution is colloidal solution or not ?
Answer: 331
331-861Colloidal solution show tyndall effect and other solutions do not show tyndall effect
Question: 332
Write electronic configuration of Chloride ion Cl-
Answer: 332
332-861Electronic configuration of Chloride ion
Question: 333
Define Mendeleev's periodic table ?
Answer: 333
333-861A 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: 334
Why are the colloids quite stable ?
Answer: 334
334-861In 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: 335
Define modern periodic law ?
Answer: 335
335-861In 1913 H.Moseley given Modern law
Properties of elements are periodic function of their atomic masses
Question: 336
How many atoms of hydrogen present in one mole of water ?
Answer: 336
336-861One 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: 337
Define unsaturated solution .
Answer: 337
337-861The solution which have capacity to dissolve more amount of solute is called unsaturated solution
Question: 338
Calculate molecular mass of sulphuric acid .
Answer: 338
338-861Molecular mass of sulphuric acid H2SO4
=2(1)+(32)+4(16)
=98amu
Question: 339
Show the state of Dynamic equilibrium in liquid and vapours with the help of diagram .
Answer: 339
339-861From 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: 340
Calculate the formula mass of the sodium sulphate .
Answer: 340
340-861Formula mass of the sodium sulphate :
Na2so4 =2(23) +(32)+4(16)
=46+32+64
=142amu
Question: 341
Why the liquid molecules are mobile ?
Answer: 341
341-861Liquid 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: 342
Define avagadro's number
Answer: 342
342-861Avagadro'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: 343
Define molarity and write its equation .
Answer: 343
343-861It is a concentration unit defined as number of moles of solute dissolved in one dm3 of solution . It is represented by M.
Question: 344
Why do suspensions not form the homogeneous mixture ?
Answer: 344
344-861The 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: 345
What is a triple covalent bond, explain with an example?
Answer: 345
345-861Ans: 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: 346
Define Boyle's law .
Answer: 346
346-861According to Boyle's law the volume of a given mass of a gas is inversely proportional to its pressure at constant temperature .
Question: 347
Give the trend of ionization energy in a period ?
Answer: 347
347-861If 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: 348
Define m0ole and give example .
Answer: 348
348-861Atomic mass , molecular mass or formula mass of a substance expressed in grams is called a mole
Question: 349
State John Dalton's atomic theory .
Answer: 349
349-861Main points of John Dalton's atomic theory are given as follows
Question: 350
Calculate the formula mass of the nitric acid .
Answer: 350
350-861HNO3 = 1+14+48
= 63amu
Question: 351
Why suspension and solutions do not show Tyndnall effect , while colloids do?
Answer: 351
351-861Solution 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: 352
What type of elements have tendency of sharing of electrons?
Answer: 352
352-861If 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: 353
Why solid show rapidly ?
Answer: 353
353-861The particles of solids are fixed at their position and are not mobile . Therefore they have rigid structure and definite shape .
Question: 354
Calculate the oxidation number of Sulphur (S) in H2SO4
Answer: 354
354-861H2SO4 = 2(+1) +(S) +4(-2)
=2=S-8
S = +6
Question: 355
Describe difference between Rutherford's theory and Bohr's atomic theory .
Answer: 355
355-861Rutherford'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: 356
Convert -30°C to K unit
Answer: 356
356-861As 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: 357
Write difference between homoatomic and heteroatomic molecules ?
Answer: 357
357-861Heteroatomic molecules:
The molecules consisting of different types of atoms are called heteroatomic molecules
Question: 358
Write down electronic configuration of phosphorous .
Answer: 358
358-861Atomic number of phosphorous is 15 Electronic configuration is given as below :
Question: 359
Calculate the oxidation number of chlorine in KClO3 .
Answer: 359
359-861{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: 360
Define periods ?
Answer: 360
360-861Seven horizontal rows present in periodic table are called periods . Numbered from 1 to 7
Question: 361
Define melting point ?
Answer: 361
361-861The temperature at which the solid starts melting and exists in dynamic equilibrium with liquid state is called melting point
Question: 362
Why drops of rain fall downward?
Answer: 362
362-861The 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: 363
What are cathode rays ? Who discovered it?
Answer: 363
363-861In 1897 JJ Thomson discovered cathode rays
Question: 364
Write down uses of radioactive isotopes as traces for diagnosis and medicine .
Answer: 364
364-8611: The radioactive isotopes are used as tracer to diagnose the presence of tumor inside the body
Question: 365
Differentiate between crystalline and amorphous solid .
Answer: 365
365-861Crystalline solid : Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solid
Question: 366
Write example of use of radioactive isotopes in the field of medicine and radiotherapy
Answer: 366
366-861In 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: 367
Define diatomic molecule and give example .
Answer: 367
367-861If a molecule consists of two atoms called diatomic molecule
Question: 368
Explain the effect of temperature on solubility .
Answer: 368
368-8611: Temperature has major affect on the solubility of most of the substances
Question: 369
Write the simplest way to distinguish between solution and pure liquid .
Answer: 369
369-861The 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: 370
Write two / four characteristics of cathode rays.
Answer: 370
370-8611: Cathode rays travel perpendicular to the cathode surface
Question: 371
Differentiate between boiling and melting point .
Answer: 371
371-861Melting point : The temperature at which the solid starts melting and exist in dynamic equilibrium with liquid state is called melting point
Question: 372
Calculate the value of angular momentum of 1st orbit where mvr = nh/2π
Answer: 372
372-861Let angular momentum (mvr) of first orbit is =mvr = nh/2π
Question: 373
Define formula mass and formula unit .
Answer: 373
373-861Formula unit : formula unit is defined as the simplest whole number ratio of ions ,as present in the ionic compounds
Question: 374
Describe two characteristics of canal rays .
Answer: 374
374-8611: 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: 375
How is the periodicity of properties depends upon the number of proton in an atom ?
Answer: 375
375-861Periodicity 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: 376
Write down the position of hydrogen in the periodic table
Answer: 376
376-861First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period
Question: 377
What is the difference between the evaporation and boiling point ?
Answer: 377
377-861Evaporation : The process of changing of a liquid into a gas phase is called evaporation .
Question: 378
Define electronic configuration . Also give example .
Answer: 378
378-861The distribution of electrons around the nucleus in various shells and sub shells according to their increasing energy is called electronic configuration.
Question: 379
Why is the formula of solute necessary for calculation of the molarity of the solution ?
Answer: 379
379-861Formula of solute is necessary for calculation of the molarity of the solution because molarity depends upon No. of moles of solute
Question: 380
What are SI units of atomic radius ?
Answer: 380
380-861Pico meter (pm) =10-12m
Question: 381
Define Dynamic equilibrium ?
Answer: 381
381-861When 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: 382
What is meant quantum ?
Answer: 382
382-861Quantum 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: 383
What is difference between colloidal and suspension ?
Answer: 383
383-861Colloid : 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: 384
How a covalent bond becomes polar?
Answer: 384
384-861When 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: 385
Define atomic radius ?
Answer: 385
385-861The half of the distance between the nuclei of the two bonded atoms referred as atomic radius
Question: 386
How do atoms follow octet rule?
Answer: 386
386-861Atoms 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: 387
What is difference between ion and free radical ?
Answer: 387
387-861Free 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: 388
How the properties of elements repeat after regular intervals?
Answer: 388
388-861The 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: 389
What are Dobereiner's triads ?
Answer: 389
389-861A 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: 390
Write electronic configuration of Mg
Answer: 390
390-861Atomic number of Mg 12
Question: 391
In which pattern modern periodic table was arranged?
Answer: 391
391-861According to increasing atomic number.
Question: 392
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: 392
392-861Electronic 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: 393
Why do the bigger size atoms have more shielding effect?
Answer: 393
393-861In bigger size atoms the number of inner shells and inner shell electrons increases hence the shielding effect in bigger size molecules also increases.
Question: 394
Who discovered proton and neutron ?
Answer: 394
394-861Proton is discovered by Goldstein in 1886
Question: 395
Define electrochemistry .
Answer: 395
395-861Electrochemistry is a branch of chemistry that deals with the relationship between electricity and chemical reaction
Question: 396
Why 2nd ionization energy of an elements is higher than first one?
Answer: 396
396-861fins: 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: 397
Why elements of group 1 and group 2 are called S block elements?
Answer: 397
397-861There are four blocks in the periodic table named after the name of the subshell which is in the process of completion by electrons .
Question: 398
Define aqueous solution . Write its components .
Answer: 398
398-861The 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: 399
Differentiate between gram atomic mass and gram molecular mass .
Answer: 399
399-861Gram atomic mass: The atomic mass of an element expressed in grams . It is called gram atomic mass
Question: 400
How many normal periods are and name also?
Answer: 400
400-8612nd and 3rd periods are known as normal periods and they are two in number
Question: 401
What is difference between solution aqueous solution ?
Answer: 401
401-861Solution : A solution is a homogenous mixture of two or more substance
Question: 402
Why do atoms react ?
Answer: 402
402-861It 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: 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
Calculate the oxidation number of nitrogen in HNO3 .
Answer: 404
404-861HNO3 = (1) +(N) +3 (-2)
= 1+N-6
N = +5
Question: 405
Describe the number of molecules in 9 g water.
Answer: 405
405-861Volume of water = 9g
Question: 406
What is a plum pudding theory ?
Answer: 406
406-861Thomson 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: 407
What is difference between solution and mixture ?
Answer: 407
407-861Solution : Homogenous mixture of two or more substance called solution
Question: 408
What are non - electrolytes .Give one example
Answer: 408
408-861The 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: 409
What are two defects in Rutherford's atomic model ?
Answer: 409
409-8611: 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: 410
Define freezing point ?
Answer: 410
410-861The temperature at which liquid and solid coexist at dynamic equilibrium is called freezing point
Question: 411
Ionic compounds conduct electricity in solution or molten form. Why?
Answer: 411
411-861Ionic 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: 412
What are weak electrolytes? . Give example .
Answer: 412
412-861The substances which ionize to a small extent when dissolved in water and could not produce more ions are called weak electrolytes
Question: 413
What is solid-solid solution ? Give two examples .
Answer: 413
413-861Alloy: When solid solvent and solid solute make solutions it is called solid-solid solution
Question: 414
What type of covalent bond is formed in nitrogen molecule?
Answer: 414
414-861In 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: 415
How can you justify that milk is a colloid?
Answer: 415
415-861Milk 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: 416
For what purpose is U-235 used ?
Answer: 416
416-861The 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: 417
Where does most of the mass of an atom exists ?
Answer: 417
417-861Most 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: 418
Why has water polar covalent bond ?
Answer: 418
418-861Water 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: 419
Metals arc good conductor of electricity. Why?
Answer: 419
419-861Metals 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: 420
What is the nature of charge on cathode ray ?
Answer: 420
420-861Cathode rays are deflected toward positive plate in an electric field showing that they are negatively charged
Question: 421
How meat can be preserved ?
Answer: 421
421-861Table 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: 422
Why is the hold of nucleus over the outermost electrons in metal weak ?
Answer: 422
422-861The 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: 423
How many sub shell are there in second sub shell ?
Answer: 423
423-861In second sub shell 'L ' has two sub shells s and p
Question: 424
Why do atoms form chemical bonds?
Answer: 424
424-861Atoms achieve stability by attaining electronic configuration of inert gases ns2 or ns2,np6 Atoms combine with one another. which is called chemical bond.
Question: 425
Define periodicity ?
Answer: 425
425-861Properties of elements were found repeating after regular intervals in periodic table it is the periodicity
Question: 426
What happens at cathode in galvanic cell ?
Answer: 426
426-861Reduction process takes place at cathode in galvanic cell
Cu+2 + 2e➜ Cu
Question: 427
What are spontaneous and non- spontaneous reaction ? Differentiate them
Answer: 427
427-861Spontaneous reaction : The reaction which proceed without any external assistance and heat are called spontaneous reaction .These reactions takes place in galvanic cells
Question: 428
Write down the position of hydrogen in the periodic table
Answer: 428
428-861First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period
Question: 429
Define solution with example .
Answer: 429
429-861A 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: 430
Give two examples of gas in liquid solution .
Answer: 430
430-8611: Fog
Question: 431
Where do electrons flow from Zn electrode in Daniel's cell ?
Answer: 431
431-861In Daniel's cell electron flow from Zn electrode to Cu electrode i-e from anode to cathode through external circuit
Question: 432
Define molar solution and give example .
Answer: 432
432-861When one mole of solute is solved on one dm3 of solvent in measuring flask then it is called one molar solution
Question: 433
Write down atomic number of nitrogen and oxygen .
Answer: 433
433-861The atomic no of N2 is = 7
Question: 434
Determine the oxidation number of Mn in KMnO4.
Answer: 434
434-861{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: 435
Which electrons are involved in chemical bonding?
Answer: 435
435-861Only valence shell electrons are involved in chemical bonding
Question: 436
Write electronic configuration of chlorine and carbon
Answer: 436
436-861Electronic configuration of carbon : 12 C 6 = 1s2 , 2s2 , 2p2
Question: 437
Define transition temperature . Give example .
Answer: 437
437-861The temperature at which one allotropes changes into another is called is called transition temperature
Question: 438
Write down the electronic configuration of following
1: Na 2: Al
Answer: 438
438-8611: Atomic number of Na 11
11Na = 1s2. 2s2 . 2p6 . 3s1
Question: 439
Differentiate duplet and octet rule.
Answer: 439
439-861Duplet Rule:
Attaining two electrons in valence called duplet rule.
Example. , Li+Hefollow duplet rule.
Question: 440
What is meant by colloid ?
Answer: 440
440-861The 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: 441
Write down the two postulates of Bohr's atomic model .
Answer: 441
441-8611: The hydrogen atom consists of a tiny nucleus and electrons are revolving in one of circular orbits of radius ' r ' around the nucleus
Question: 442
Why does atomic size increases in a group ?
Answer: 442
442-861The 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: 443
Write two examples of gas into gas solution .
Answer: 443
443-8611:Air
Question: 444
Write electronic configuration of Boron .
Answer: 444
444-861Atomic no of Boron 5
Question: 445
What type of solutions butter and smoke are ?
Answer: 445
445-861Solution : Butter , smoke
Question: 446
What is effective nuclear charge ?
Answer: 446
446-861The valence electron of an atom experiences less nuclear change than that of actual charge , it is called effective nuclear charge or Zeff
Question: 447
Write down the trend of atomic size in the periodic table.
Answer: 447
447-861In period : Atomic size in a period from left to right decreases
Question: 448
Why do the colloids show tydnall effect ?
Answer: 448
448-861Colloids shows tyndall effect because the particles of
” colloids scatter the path of light rays due to large size.
Question: 449
Define transition element ?
Answer: 449
449-861d block elements called transition element
Question: 450
Define carbondating .
Answer: 450
450-8611: 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: 451
How atoms accommodate 8 electrons in their valence shells?
Answer: 451
451-861toms 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: 452
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: 452
452-861Elements in group 3 to 12 elements are normal elements because their valence electrons lie in s and p sub shell
Question: 453
How are elements are arranged in 4th period ?
Answer: 453
453-861In fourth period 18 elements are arranged in the ascending order of their atomic number
Question: 454
What is general principle of solubility ?
Answer: 454
454-861The 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: 455
Wrote the observations made by Rutherford .
Answer: 455
455-861Observations made by Rutherford are as follows :
Question: 456
Define oxidation in terms of electrons and give an example .
Answer: 456
456-861Oxidation : The loss of electron by an atom or ion is called oxidation
Question: 457
Why ionization energy of Na is less than Mg ?
Answer: 457
457-861Ionization energy of Na is less than Mg because Mg has greater nuclear charge than Na and also have smaller size
Question: 458
Describe difference between concentrated and dilute solution .
Answer: 458
458-861Concentrated solution : The solution which contains relatively large amount of dissolved solute in solution is called concentrated solution
Question: 459
Differentiate bonding electrons and non-bonding electrons•
Answer: 459
459-861The 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: 460
Why solution is considered mixture ?
Answer: 460
460-861The 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: 461
What are difference between string and weak electrolytes .
Answer: 461
461-861Strong electrolyte : The substance which ionizes completely in solution to produce more ions which can conduct strongly is called strong electrolyte
Question: 462
Why ionization energy decreases in a group from top to bottom ?
Answer: 462
462-861When 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: 463
Define electrochemical cell . With the names of its types .
Answer: 463
463-861Electrochemical 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: 464
Why water is called universal solvent ?
Answer: 464
464-861Water is called universal solvent because it dissolves almost all the solute particles present in the world
Question: 465
Give the characteristics properties of ionic compounds
Answer: 465
465-861the 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: 466
What is meant by periodic function ?
Answer: 466
466-861Repetition of properties due to increases of atomic number after regular intervals in the periodic table is called periodic function
Question: 467
Give difference between solution and colloids .
Answer: 467
467-861Colloids :
The particles of colloids are large consisting of many atoms , ions , or molecules
Question: 468
What is the relationship between evaporation and boiling point of a liquid?
Answer: 468
468-861Boiling 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: 469
Why is the bond between an electropositive and an electronegative atom ionic in nature ?
Answer: 469
469-861Because 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: 470
How many electrons will be in M shell of an atom having atomic no 15?
Answer: 470
470-861Atomic number 15
K shall = 2 electrons
L shall = 8 electrons
M shall = 5 electrons
Question: 471
What is solid-liquid solution ? Explain with example .
Answer: 471
471-861When 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: 472
Why the electrons move freely in metals ?
Answer: 472
472-861This 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: 473
What is meant by ' Like dissolves like'
Answer: 473
473-8611: 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: 474
Which is the simplest form of matter?
Answer: 474
474-861Gas is the simplest form of matter.
Question: 475
How mass number of same elements are different ?
Answer: 475
475-861Isotopes 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: 476
Why the density of a gas is measured in gdm-3while that of a liquid is expressed in gcm-3?
Answer: 476
476-861The 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: 477
Write difference between electrolytic cell and galvanic cell.
Answer: 477
477-861Electrolytic 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: 478
Write any four examples of colloidal solution .
Answer: 478
478-8611: Starch
Question: 479
How much NaOH is required to prepare its 500cm3 of 0.4m solution?
Answer: 479
479-861Molar mass of NaOH =40gmol-3
Question: 480
Why we stir paints thoroughlybefore use ?
Answer: 480
480-861Paint 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: 481
Why does group 1 elements prefer to combine with group 17 elements.
Answer: 481
481-861The 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: 482
Write electronic configuration of Neon and Berylium
Answer: 482
482-861Atomic number of Neon 10
Question: 483
Why size of an atom decreases from left to right in the periodic table?
Answer: 483
483-861When 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: 484
Identify as colloids and suspensions : paints, jelly, soap solution , milk , milk of magnesia , chalk in water .
Answer: 484
484-861Colloid : Soap solution , Milk , Jelly
Suspension : paints , milk of magnesia , chalk in water
Question: 485
What characteristics properties do the covalent compound have ?
Answer: 485
485-861They 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: 486
What is the shape of cathode in the Nelson's cell ? Why is it perforated ?
Answer: 486
486-861The cathode in Nelson's cell is U- shaped . It is perforated for the percolation of NaoH into a catch basin
Question: 487
What do you mean by induced dipole?
Answer: 487
487-861The charges in one molecule creates charges in other molecules these charges are called induced dipole.
Question: 488
How many members are in group 17, is there any liquid, what is its name?
Answer: 488
488-861There 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: 489
Which form of Sulphur exists at room temperature?
Answer: 489
489-861Rhombic (S8) Sulphur exists at room temperature
Question: 490
Give two examples of suspension .
Answer: 490
490-8611: In suspension the undissolved particles are big enough to be seen with the naked eye
Question: 491
What is difference between valency and oxidation ?
Answer: 491
491-861Valency : Valency is the combining capacity of an atom with other atoms . It depends upon the number of electrons in the outermost shell
Question: 492
Why does rate of diffusion increase with increase of temperature?
Answer: 492
492-861Diffusion increases by increasing temperature because at high temperature the in termolecular forces become weak due to high kinetic energy of the molecules
Question: 493
Name the element of 1st period of periodic table
Answer: 493
493-8611st period consists only two elements hydrogen (H2|) and Helium ( He)
Question: 494
Describe exothermic reaction with example .
Answer: 494
494-861Exothermic 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: 495
Define corrosion ?
Answer: 495
495-861Corrosion 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: 496
Define reduction on the basis of electron and give example .
Answer: 496
496-861Reduction reaction : The gain of electrons by atom or ion is called reduction reaction .
Question: 497
What are electrolytes or non-electrolytes ?
Answer: 497
497-861Electrolytes : The electrolytes which can conduct electricity in their aqueous solution of fuse form and produce more ions are called electrolytes
Question: 498
What is an electron affinity ? Give an example .
Answer: 498
498-861Trend 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: 499
What type of solution fog and brass are?
Answer: 499
499-8611: Fog is a solution of liquid solute in gas solvent
Question: 500
Define triads and law of octaves .
Answer: 500
500-861Triads : The group of three elements called triads . In these groups central and middle element had atomic mass average of the other two element
Question: 501
Why noble gases are non-reactive?
Answer: 501
501-861The 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: 502
Write any two properties of solution and suspension
Answer: 502
502-861Solution :
1: A solution is a homogeneous mixture of two or more substances
Question: 503
Why are the liquids mobile.
Answer: 503
503-861Liquid 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: 504
Write two uses of isotopes
Answer: 504
504-8611: In the field of medicine isotopes of iodine 131 are use for diagnose of goiter in thyroid gland
Question: 505
Why the rate of diffusion of gases is rapid than that of liquid ?
Answer: 505
505-861The 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: 506
What is difference between Duplet rule and octet rule ?
Answer: 506
506-861Duplet rule : Attaining two electrons in the valence shell is called duplet rule
Question: 507
Which type of electron are responsible for holding the atoms together in metals ?
Answer: 507
507-861Nuclei 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: 508
Write any two rules for assigning oxidation number .
Answer: 508
508-8611: The oxidation number (O.N) of an ion consisting on a single element is the same as the charge on that ion .
Question: 509
How much amount of KOH required to form 1 molar solution ?
Answer: 509
509-861Concentration of solution = 1dm3
Molar mass of KOH = 39+16+1
= 56 mol
Question: 510
For what purpose C-14 is used ?
Answer: 510
510-861Uses of C-14
Question: 511
What is tyndall effect ? On which factor it depends ?
Answer: 511
511-861Tydnall effect: The particles of colloids are big enough to scatter the beam of light . It is called tydnall effect
Question: 512
Which is lighter one aluminium or gold?
Answer: 512
512-861Aluminum is lighter than gold because density or aluminium is 2.70 gcm'-3 While of gold is 9.3 gcm-3
Question: 513
What is difference between group and period ?
Answer: 513
513-861Group : The vertical columns present in periodic table are called groups .There are 18 groups present in the periodic table
Question: 514
Define super-saturated solution .
Answer: 514
514-861The solution that is more concentrated than a saturated solution at a given temperature is known as super- saturated solution
Question: 515
Why suspension does not form homogeneous mixture?
Answer: 515
515-861sn, Particles remain un dissolved and from a heterogeneous mixture. Particles settle down after some times.
Question: 516
What is salt bridge ? What is its basic function ?
Answer: 516
516-861Galvanic cell consists of two half cells, both these half cells are connected by salt bridge
Question: 517
What is periodic law?
Answer: 517
517-861In 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: 518
What is the sign of stability of an atom ?
Answer: 518
518-861The 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: 519
What is meant by true solution ?
Answer: 519
519-861True 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: 520
Define reduction .
Answer: 520
520-861Reduction is defined as addition of hydrogen or removal of oxygen during a chemical reaction
Question: 521
Why are dipole forces of attraction not found in halogen molecules?
Answer: 521
521-861Dipole forces of attraction do not found in halogen molecules because they have same electronegativity and there is equal sharing of electrons.
Question: 522
Define Mendeleev's periodic law .
Answer: 522
522-861Mendeleev 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: 523
What does mean rusting of iron ?
Answer: 523
523-861Corrosion of iron is called rusting . The important condition for rusting is moist air
Question: 524
Define solubility ?
Answer: 524
524-861The amount of solute in grams dissolved in 100g of solvent to prepare saturated solution at a particular temperature is called solubility of solute .
Question: 525
Why ionic compounds easily dissolve in water?
Answer: 525
525-861They dissolve easily in water because water is a polar solvent and has high dielectric constant that weakens the attraction between ions.
Question: 526
Which isotopes are called radioactive isotopes ?
Answer: 526
526-861The isotopes have ability to emit radiation naturally called radioactive isotopes
Question: 527
What is galvanizing ?
Answer: 527
527-8611: The process of coating a thin layer of zinc on iron is called galvanizing
Question: 528
Define Shielding effect.
Answer: 528
528-861The 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: 529
What is difference between polar and non-polar covalent bonds, explain with one example of each?
Answer: 529
529-861Polar 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: 530
Define redox reaction , Give an example .
Answer: 530
530-861The reaction in which oxidation as well as reduction takes place at a time called redox reaction
Question: 531
Why does true solutions not show Tyndall effects?
Answer: 531
531-861True 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: 532
Why is white tin available at room temperature?
Answer: 532
532-861White tin available at room temperature because it is stable at room temperature above 13.2°C
Question: 533
How will you test whenever given solution is colloidal solution or not?
Answer: 533
533-861If 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: 534
Define noble gases and give example .
Answer: 534
534-861Elements 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: 535
Why do ionic compounds conduct electricity in solution or molten form?
Answer: 535
535-861Ionic compounds are good conductor in solution and molten form due to the presence of free ions in them
Question: 536
Which are long periods ? How many elements are present in long periods ?
Answer: 536
536-8614th 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: 537
Differentiate between Lone pair and bond pair of electrons .
Answer: 537
537-861Long pair : The pair of electrons which remain unshared during covalent bond formation is called long pair
Question: 538
Which metal is used for the galvanizing of iron ?
Answer: 538
538-861Zinc metal is used for galvanizing of iron because it protects from corrosion
Question: 539
Define oxidation and give example .
Answer: 539
539-861Oxidation reaction : The loss of electron by an atom or ion is called oxidation .
Question: 540
What is electronegativity ? Write its unit .
Answer: 540
540-861The ability of an atom to attract the shared pair of electrons towards itself in a molecule is called electronegativity
Question: 541
Define electrolysis and give example .
Answer: 541
541-861The decomposition of compound by passing electric current through molton or aqueous solution of the compound called electrolysis
Question: 542
What is difference between Mendeleev's periodic law and modern periodic law?
Answer: 542
542-861Mendeleev's periodic law : The properties of elements are the periodic function of atomic masses
Question: 543
How molar solution is prepared ?
Answer: 543
543-861One 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: 544
Identify a strong and weak electrolyte among the following compound
- CuSO4 , Ca (OH)2 , HCL , HNO3
Answer: 544
544-861Strong electrolyte :HCL ,HNO3 AND CuSO4 are strong electrolyte
Question: 545
Give two characteristics of colloid .
Answer: 545
545-8611: Colloid particles are large but can't be seen with naked eyes
Question: 546
Differentiate between solute and solvent ?
Answer: 546
546-861Solute : The component which is present in smaller quantity is called solutee.g : Salt in water , salt is solute
Question: 547
State Charles's law
Answer: 547
547-861The volume of a given mass of a gas is directly proportional to the absolute temperature when pressure kept constant."
Question: 548
Write two uses of redox reaction .
Answer: 548
548-861Redox reaction are useful in batteries to produce energy and this electricity is used to drive non-spontaneous reaction
Question: 549
Why big size covalent molecules have high melting and boiling points?
Answer: 549
549-861Bigger molecules with three dimensional bonding form covalent crystals which are very stable and have high melting and boiling points.
Question: 550
Write down electronic configuration of sodium .
Answer: 550
550-861Electronic configuration of sodium
11Na = 1s2 , 2s2 , 2p6 , 3s1
Question: 551
Define standard atmospheric pressure . What are its units ? How it is relate to the pascal ?
Answer: 551
551-861It is defined as the pressure exerted by a mercury column of 760 mm height at sea level
Question: 552
Define chemical bond and write names of its type .
Answer: 552
552-861A 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: 553
Why test tube becomes cold when KNO3 is dissolved in water ?
Answer: 553
553-861The dissolution of KNO3 in water is an endothermic process in which heat absorbed when KNO3 dissolve in test tube it becomes cold
Question: 554
What ammendment was made by H.Moseley in mendeleev periodic table ?
Answer: 554
554-861According 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: 555
In electroplating of silver, from where Ag+ ions come and where they deposit?
Answer: 555
555-861In 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: 556
What types of electron pairs make a molecule good donor ?
Answer: 556
556-861The lone pair of electron make a molecule a good donor
Question: 557
What is the reason of deficiency of electrons in BF3?
Answer: 557
557-861In 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: 558
What type of elements form metallic bond?
Answer: 558
558-861Metals form metallic bond
Question: 559
Where sodium metal is obtained from fused sodium chloride .
Answer: 559
559-861Sodium metal accumulates at iron cathode in down's cell
Question: 560
Why the elements of group 13 to group 18 are called P block elements ?
Answer: 560
560-861Elements of group 13 to 18 have their valence electrons in P subshell . Therefore , they are called as P-block elements
Question: 561
What is transition temperature of sulphur?
Answer: 561
561-861Its transition temperature is 96℃.
Question: 562
Classify the following into true solution and colloidal solution?
Answer: 562
562-861Blood, 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: 563
Define electrolyte . Give an example .
Answer: 563
563-861Electrolyte : The substance which can conduct electricity in their solution or molten states are called electrolytes . Salts and acids are good electrolytes
Question: 564
Difference between substance and mixture.
Answer: 564
564-861Substance: A piece of matter in pure form is termed as substance.
e.g. Glucose (C6H12O6) Oxygen
Question: 565
What is atomic number of Sulphur ? Write down its electronic configuration .
Answer: 565
565-861Atomic number of Sulphur IS 16 .
Question: 566
Write down the reaction occuring on cathode and anode during the electrolysis of water .
Answer: 566
566-861Following reactions occur at anode and cathode during electrolysis of water
Question: 567
For what purpose P-32 and Sr - 90 are used .
Answer: 567
567-8611: For the treatment of skin cancer , isotopes like P-32 and Sr-90 are used because they emit less penetrating beta radiations
Question: 568
Identify strong or weak electrolyte among the following
CuSO4 , H2CO3 ,(OH)2 , AGNO3 , Ca (OH)2
Answer: 568
568-861Strong electrolyte :HCL,HNO3 and CuSO4. AgNO3 are strong electrolyte
Question: 569
What is difference between corrosion and rusting ?
Answer: 569
569-861Corrosion : 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: 570
How can you justify that blood is a colloid?
Answer: 570
570-861Blood 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: 571
Define effective nuclear charge .
Answer: 571
571-861In 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: 572
Differentiate saturated and unsaturated solution
Answer: 572
572-861Saturated : A solution containing maximum amount of solute at a given temperature is called saturated solution
Question: 573
Describe difference between true solution and colloid .
Answer: 573
573-861True 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: 574
Write two physical properties of magnesium .
Answer: 574
574-861Magnesium is good conductor of heat and electricity
Question: 575
How iron is prevented from rust by tin coating ?
Answer: 575
575-8611:It involves the dipping of the clean sheet of iron in a bath of molten tin and then passing it through hot rollers
Question: 576
Why dose ice float on water?
Answer: 576
576-861lCe 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: 577
Write down names of elements of first group and second period of the periodic table .
Answer: 577
577-861First group of periodic table consists of hydrogen , lithium , sodium , potassium , rubidium , cesium , francium
Question: 578
What type of bond exists in ionic compound?
Answer: 578
578-861Ionic bond exists in ionic compound.
Question: 579
Why is melting point of a solid considered its 'identification' characteristics ?
Answer: 579
579-861The 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: 580
What do you mean by delta sign and why it develop ?
Answer: 580
580-861The 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: 581
How many blocks are present in periodic table ?
Answer: 581
581-861There are4 presentin periodic table called s, p, d and f block
Question: 582
Does Kelvin scale show negative temperature?
Answer: 582
582-861No. Kelvin scale does not show a negative temperature
Question: 583
What is the nature of electrode used in electroplating of chromium?
Answer: 583
583-861The object to be electroplated acts as cathode while anode is made of antimonial-lead.
Question: 584
Define oxidation and reduction reaction .
Answer: 584
584-861Oxidation: Oxidation is defined as addition of oxygen or removal of hydrogen or electron during a chemical reaction
Question: 585
Differentiate between donor atom and acceptor atom.
Answer: 585
585-861Donor atom : The atom which donates the electron pair in coordinate covalent bond is called donor atom
Question: 586
Why do ionic compound conduct electricity in solution form . Give reason
Answer: 586
586-861Ionic 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: 587
Give the electronic configuration of carbon atom.
Answer: 587
587-861Atomic no. of carbon = Z= 6
No of electrons in carbon atom =Z=6
Electronic configuration of carbon atom=ls2.2s2,2p2
Question: 588
What is galvanic cell? Give an example .
Answer: 588
588-861The electrochemical cell in which a spontaneous chemical reaction takes place and generates electric current is called galvanic or voltaic cell
Question: 589
What is the trend of ionization energy in the group ?
Answer: 589
589-861As 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: 590
Define oxidation in terms of oxygen with an example .
Answer: 590
590-861Oxidation : The addition of oxygen in any chemical reaction is called oxidation reaction
Question: 591
Two hydrogen atoms combine to form molecules H2 while 'He' atom remains monatomic . Explain ?
Answer: 591
591-861Two 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: 592
Define oxidizing and reducing agents with example .
Answer: 592
592-861Oxidizing 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: 593
What is percentage-mass/mass(%m/m)?
Answer: 593
593-861It is the number of grams of solute in 100 grams of solution
Question: 594
Explain Dobereiner's triads .
Answer: 594
594-861Dobereiner 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: 595
Define the term allotropy ?
Answer: 595
595-861Allotropy: The existence of an element in more than one forms in same physical state is called allotropy.
Question: 596
What is the principle of electroplating ?
Answer: 596
596-861Principle 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: 597
Give the reason for the decrease of electronegatively in down the group .
Answer: 597
597-861Electronegatively decreases down a group because size of the atom increases . The attraction for the shared pair of electrons weakens
Question: 598
Why Lanthanides an Actanides are placed separately below periodic table . Explain
Answer: 598
598-861Because 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: 599
Which is most precious metal ?
Answer: 599
599-861The most precious metal is platinum
Question: 600
What will happen if the pressure temperature is kept constant?
Answer: 600
600-861The volume of gas will decrease three times when its pressure raised up to three times as temperature.
Question: 601
Define Electrochemistry.?
Answer: 601
601-861Electrochemistry is the branch of chemistry which deals with the relationship b-cl electricity and chemical reactions.
Question: 602
Name the elements of first group .
Answer: 602
602-8611: Hydrogen (H)
Question: 603
Why we stir paint thoroughly before using?
Answer: 603
603-861We 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: 604
Write uses of magnesium .
Answer: 604
604-8611: Magnesium is used in flash light bulbs and in fireworks .
Question: 605
What are anode or cathode ?
Answer: 605
605-861Anode : It is the electrode at which the oxidation takes place
Question: 606
Why gases are compressible ?
Answer: 606
606-861Gases 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: 607
How many neutrons are there in C-12 , C-13 ?
Answer: 607
607-8611: C-12 has 06 neutrons
2: C-13 has 07 neutrons
Question: 608
Define metallic character .
Answer: 608
608-861The property of a metal to loose its valence electrons to form a positive ion is called metallic character
Question: 609
State whether allotropy is shown by elements or compounds or both ?
Answer: 609
609-861Allotropy is only shown by elements . It is not a property of compounds
Question: 610
How galvanizing of iron sheets is done ?
Answer: 610
610-861The 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: 611
What is meant by atomic radius ? What is its unit ?
Answer: 611
611-861The half of the distance between the nuclei of two of similar adjacent (bonded) atoms is called atomic radius
Question: 612
Compare two physical properties of metals and non-metals .
Answer: 612
612-861Metal :
1:Almost all metals are solid (except mercury) they have high densities
Question: 613
Why does a dipole develop in a molecule ?
Answer: 613
613-861The 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: 614
What is meant by electroplating ?
Answer: 614
614-861Electroplating is depositing of one metal over the other by means of electrolysis
Question: 615
Why elements are called s and p block elements ?
Answer: 615
615-861Elements are called s and p block elementsbecause their last element is present in s and p sub shell
Question: 616
Write chemical reaction that takes place during working of Nelson's cell.
Answer: 616
616-861Following reactions take place in Nelson's cell
Ions formed in Brine
2NaCl (aq)➜ 2Na+ (aq) +2Cl(aq)
Question: 617
Why sodium metal is more reactive than magnesium ?
Answer: 617
617-861Magnesium 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: 618
Write down the electronic configuration of fluorine and Neon
Answer: 618
618-861Electronic configuration of fluorine:
9F=1s2 , 2s2 , 2p4
Question: 619
Write down use of paints and greases .
Answer: 619
619-8611: Greasing or painting of the surface can prevent the corrosion of iron
Question: 620
How metallic character is changes in a group of periodic table ?
Answer: 620
620-861Metallic character increase in a group from top to bottom due to increase in the size of atoms
Question: 621
What are trends of ionization energy in periodic table ?
Answer: 621
621-861Ionization energy increases from left to right in the period while it decreases from to bottom in a group
Question: 622
What is the half cell reactions occuring on cathode and anode in Daniel cell ?
Answer: 622
622-861Following reactions occur at cathode and anode in Daniel cell .
Question: 623
When a gas is allowed to expand, what will be its effect on its temperature?
Answer: 623
623-861According to Charles' Law when gas is allowed to expand its temperature also increases.
Question: 624
If repulsive forces dominate to attractive forces will a covalent bond form?
Answer: 624
624-861If 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: 625
Define Newland octaves law ?
Answer: 625
625-861In 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: 626
Name the metal which is least conductor of heat ?
Answer: 626
626-861Lead is a metal which is least conductor of heat
Question: 627
What is meant by metallic bond ?
Answer: 627
627-861When positively charged metal ions are held together by freely moving electrons , the bond which is formed called metallic bond
Question: 628
Why the 2nd ionization energy is greater than 1st ionization energy ?
Answer: 628
628-861Because 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: 629
Why is BF3, electron deficient?
Answer: 629
629-861In 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: 630
What is relation between electropositivity and ionization energy ?
Answer: 630
630-861Electropositivity is the reverse of the ionization energy . In the from from top to bottom ionization energy decreases and electropositivity increases
Question: 631
Define Bond pair ?
Answer: 631
631-861The valence electrons which take part in covalent bond is called bonding electrons . These electrons present in the incomplete valence shell
Question: 632
What do you mean by malleability?
Answer: 632
632-861Malleability is the property by virtue of which metals can be drawn into sheets.
Question: 633
What is the trend of variation in densities of alkali metals?
Answer: 633
633-861Densities of alkali metals increases down the group in the periodic table
Question: 634
Why covalent bond in H2 is non-polar ?
Answer: 634
634-861In 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: 635
Write symbol of any four elements of halogen .
Answer: 635
635-8611: Flourine (F)
Question: 636
In which form sulphur exists at I00°C?
Answer: 636
636-861Sulphur 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: 637
how can you explain the solute-solvent interaction to prepare NaCI Solution?
Answer: 637
637-861When 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: 638
What is meant by dipole dipole forces of attraction ?
Answer: 638
638-861When 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: 639
What do you know about the construction of an electrolytic cell?
Answer: 639
639-861An 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: 640
Can pure gold be used for making ornaments?If not why?
Answer: 640
640-861No. 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: 641
What do you mean by evaporation and how it is affected by surface area?
Answer: 641
641-861Evaporation: 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: 642
Why atoms form bond ?
Answer: 642
642-861It 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: 643
Why alkali metals are extremenly reactive ?
Answer: 643
643-861Alkali 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: 644
Whether the density of a gas decreases on cooling ?
Answer: 644
644-861The density of gas increase by cooling because their volume decreases
Question: 645
Define non polar covalent bond and give example .
Answer: 645
645-861Non polar covalent bond is formed between two similar atoms the hsred pair of electrons is attracted by both the atom equally
Question: 646
Describe trend of shielding effect in periodic table .
Answer: 646
646-861The 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: 647
How many groups and period and periods are there in modern periodic table
Answer: 647
647-8611: Long form of periodic table consists of seven horizontal rows called periods
Question: 648
Which metal is used for metal work?
Answer: 648
648-861As 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: 649
What do you means by 24 carat gold ?
Answer: 649
649-8611: Purity of gold is show by carats .
Question: 650
Why is galvanizing done?
Answer: 650
650-861The 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: 651
For what purpose , Iodine-131 is used ?
Answer: 651
651-861Isotopes of iodine I-131 is used to diagnose goiter in thyroid
Question: 652
What is diffusion ? Explain with example ?
Answer: 652
652-861Diffusion is defined as spontaneous mixing up of molecules by random motion and collisions to form a homogeneous mixture
Question: 653
Which solution is used as an electrolyte in Nelson's cell ?
Answer: 653
653-861In Nelson cell concentrated solution of sodium chloride is used . It is called brine solution
Question: 654
What is absolute zero?
Answer: 654
654-861It is the temperature at which an ideal gas would have zero volume.
Question: 655
Define electrolytes and electro chemical cell .
Answer: 655
655-861Electrolytes : The substances , which can conduct electricity in their aqueous solution or molten state , are called electrolytes
Question: 656
Why suspensions and solutions do not show Tyndall effect , while colloids do ?
Answer: 656
656-861Suspensions 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: 657
Give uses of platinum
Answer: 657
657-861Uses of platinum :
1: Platinum is used in hard disk coating and in maufacturing fibre optic cables
Question: 658
Which salt is used as electrolyte in chromium electroplating ?
Answer: 658
658-861In electroplating of chromium Sulphate Cr2(SO4)3 is used an electrolyte
Question: 659
Give the reaction of mangnesium with O2 And N2 .
Answer: 659
659-861Reaction of magnesium with O2 :
They are less reactive towards oxygen and oxides are formed on heating
2Mg + ➜ 2MgO
Question: 660
What is the percentage m/volume ?
Answer: 660
660-861It is the number of grams of solute dissolved in 100cm3of solution
Question: 661
Is sign of (0) used on Kelvin?
Answer: 661
661-861No. Degree sign (°) is used with Celsius scale not with Kelvin scale.
Question: 662
Why platinum is used as for making jewellery ?
Answer: 662
662-861Platinum 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: 663
Why are the rates of diffusion in liquids slower than that of gases?
Answer: 663
663-861In 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: 664
Why the ionic compounds have high melting and boiling points?
Answer: 664
664-861Ionic 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: 665
What are the elements arranged in group 3 to 12 called ?
Answer: 665
665-861The groups 3 to 12 are called transition elements . In these elements 'd ' sub shell is in the process completion
Question: 666
What is by-products are produced in Down's cell?
Answer: 666
666-861Chlorine is produce in the downs cell as a by product
Question: 667
What is difference between electron affinity and electron -negativity ?
Answer: 667
667-861Electron affinity : Energy emitted due to the absorption of an electron in gaseous atom of an element is called electron affinity .
Question: 668
Write two physical properties of sodium hydroxide .
Answer: 668
668-8611: NaOH is crystalline solid at room temperature
Question: 669
Differentiate between oxidation and reduction.
Answer: 669
669-861Oxidation : Oxidation is defined as addition of oxygen or removal of hydrogen during a chemical reaction
e.g
ZnO + C➜Zn +CO2
Question: 670
What is stainless steel?
Answer: 670
670-861Stainless steel is an alloy which is formed by the combination of iron , ,chromium and nickel
Question: 671
Why chlorine can accept only 1 electron?
Answer: 671
671-861Chlorine 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: 672
Define brine ?
Answer: 672
672-861The by-product in Nelson's cell are hydrogen gas (H2) and chlorine gas (Cl2)
Question: 673
Why is vapour pressure higher at high temperature?
Answer: 673
673-861At 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: 674
How platinum is used as a catalyst in automobiles?
Answer: 674
674-861Platinum 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: 675
Why silver is not used in pure form ?
Answer: 675
675-861Silver is a very soft metal that's why it is not used as such in pure
Question: 676
What is meant by octet rule ?
Answer: 676
676-861Attaining 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: 677
Which force drives the non-spontaneous reaction to take place ?
Answer: 677
677-861Non-spontaneous reactions are those which take place in the presence of an external agent . These reactions takes place in galvanic and electrolytic cells
Question: 678
What do you mean by 24 carat gold ?
Answer: 678
678-861Purity 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: 679
An element X has oxidation state 0 . What will be the oxidation state when it gains three electrons ?
Answer: 679
679-861Suppose the element x
X0 +3e-➜ X-3
Question: 680
Define metal and give two examples .
Answer: 680
680-861The elements which have ability to lose electron and forms cations called metals like Na , K , Ca
Question: 681
Molecular formula of a sulphur molecule
Answer: 681
681-861The Molecular formula of a sulphur molecule S8
Question: 682
Describe at least two necessary conditions for the formation of covalent bond .
Answer: 682
682-8611: A covalent bond is formed between two non-metals
Question: 683
Why fluorine is more non-metallic than chlorine ?
Answer: 683
683-861Fluorine is more reactive than chlorine because the electronegativity of fluorine is greater tahn chlorine
Question: 684
What is the difference between steel and stainless steel ?
Answer: 684
684-861Steel is a mixture while stainless steel is an alloy
Question: 685
What is the reason for the difference between solutions, colloids and suspensions?
Answer: 685
685-861Particles 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: 686
Give the non-metallic trend in halogens .
Answer: 686
686-861Elements 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: 687
What is the colour of flame when sodium and calcium burn in air ?
Answer: 687
687-8611: Sodium burns in air and produce golden yellow flame
Question: 688
What is difference between short period and ling period ?
Answer: 688
688-861Short period : First period of periodic table is called short period . It consists of Hydrogen and Helium
Question: 689
Write the symbol of noble gasses
Answer: 689
689-8611: Helium (He)
Question: 690
Complete the following chemical equation .
Answer: 690
690-861NaO +H2O➜ 2NaOH
Question: 691
What happens to iron in the rusting process ?
Answer: 691
691-861The oxidation of iron take place during rusting process and forms Fe2O3 . The chemical formula of rust is Fe2O3nH2O
Question: 692
Define solution ?
Answer: 692
692-861A solution is homogenous mixture of two or more substances
Question: 693
Write reaction of chlorine with hydrogen and water
Answer: 693
693-861Reaction of hydrogen with chlorine
Cl2 +H2O ➜ HCL +HOCL
Question: 694
What are metalloids ? Give two examples .
Answer: 694
694-861The elements whose properties are intermediate between metals and non-metals are called metalloids
Question: 695
What is metallic coating ?
Answer: 695
695-861For the protection against the rusting metals are coated with other metal and it is called metallic coating.
Question: 696
How can we distinguish a metal from non-metal by a simple physical method ?
Answer: 696
696-861Metals : On heating metals usually become soft and flexible
They are difficult to cut
Question: 697
What are electrolytic cell ?
Answer: 697
697-861Electrolytic 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: 698
Why is ionization energy of sodium is less than magnesium ?
Answer: 698
698-861Ionization 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: 699
Why does sodium form a chemical bond with chlorine ?
Answer: 699
699-861Sodium 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: 700
Define the coordinate covalent bond? Explain with one example .
Answer: 700
700-861Coordinate 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: 701
How oxygen react with group-2 metals?
Answer: 701
701-861They are less reactive towards oxygen and oxides are formed on heating
Question: 702
Define biotechnology?
Answer: 702
702-861It deals practical of living organism to make substances for the welfare of mankind
Question: 703
Define ionization energy .
Answer: 703
703-861Ionization 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: 704
Why does covalent bond become polar?
Answer: 704
704-861If 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: 705
In electroplating of chromium which salts is used as an electrolyte?
Answer: 705
705-861In electroplating of chromium, Cr2(SO4)3, is used as an electrolyte.
Question: 706
State any four physical properties of metals.
Answer: 706
706-861Physical 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: 707
What type of attractive forces exist between HCL molecules ?
Answer: 707
707-861Dipole-dipole attractiveforces exist between HCL molecules.
Question: 708
Define shielding effect , Describe its trend in a period
Answer: 708
708-861Shielding 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: 709
Why volume of a gas decreases with increase of pressure"
Answer: 709
709-861The 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: 710
What is the relationship between electro positivity and ionization energy ?
Answer: 710
710-861Electronegativity depends upon the ionization energy which is in turn depends upon size and nuclear charge of the atom
Question: 711
Differentiate between molecular mass and formula mass, which of the following will be molecular formula?
Answer: 711
711-861H2O,NaCl, KI, H2SO4
Question: 712
What is pacemaker ?
Answer: 712
712-861A 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: 713
Why arc the densities of gases tower than that of liquids?
Answer: 713
713-861Gases has e low density than liquids and solids. It is due to light mass and more volume occupied by the gas molecules.
Question: 714
Magnesium has electronic configuration 2,8,2 .Why magnesium tend to lose electron ?
Answer: 714
714-861electronic 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: 715
What do you mean by horticulture and how it is related agriculture ?
Answer: 715
715-861It 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: 716
What do you mean like dissolve like ? Explain with example ?
Answer: 716
716-861The 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: 717
Can, you cool a gas by increasing its volume
Answer: 717
717-861No. we cannot cool a gas by increasing its volume
Question: 718
How electropositivity depends upon the nuclear charge of an atom ?
Answer: 718
718-861Left 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: 719
Why is calcium more electropositive than magnesium ?
Answer: 719
719-861Calcium is more electropositive than magnesium due to its large atomic size and less amount of ionization energy
Question: 720
Define aqueous solution
Answer: 720
720-861The solution which is formed by dissolving a substance in water is called an aqueous solution
Question: 721
Define hydrogen bonding ?
Answer: 721
721-861Th 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: 722
hat is the importance of oxygen and carbon dioxide for plants and animals ?
Answer: 722
722-861Life 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: 723
Which metals are the most malleable and ductile ?
Answer: 723
723-861Gold (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: 724
What is absolute temperature scale?
Answer: 724
724-861Lord 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: 725
Explain the law of flow of heat ?
Answer: 725
725-861In 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: 726
Why shielding effect of electron makes cation formation easy ?
Answer: 726
726-861Shielding 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: 727
How sodium metal is obtained from fused sodium chloride .
Answer: 727
727-861On 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: 728
Why do electrodes get their names "anode" and cathode in galvanic cell?
Answer: 728
728-861In galvanic, cell. Oxidation take place at anode while reduction take place at cathode
Question: 729
Write down two uses of gold .
Answer: 729
729-861Because 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: 730
Why magnesium is harder than sodium?
Answer: 730
730-861Magnesium 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: 731
Which variables are kept constant in Charles' law?
Answer: 731
731-861Pressure is kept constant in Charles' law
Question: 732
What is the nature of electrode used in electroplating chromium ?
Answer: 732
732-861During electroplating chromium the object to be electroplated act as cathode with anode is made up of antiamonial lead
Question: 733
What are metalloides ? Gibe two examples
Answer: 733
733-861The elements have characteristics of both metals and non-metals are called metalloids
Question: 734
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: 734
734-861All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state
Question: 735
Write the redox reaction taking place during the electroplating of chromium.
Answer: 735
735-861Reaction at the electrodes are as Follows:
At anode 40H-➜2H2O+O2+4e-
At cathode C+33e-➜Cr
Question: 736
Define alloy and give example .
Answer: 736
736-861Alloy : alloy is a homogeneous mixture of one metal with one or more metals or non-metals
Question: 737
6: Complete the following chemical equation :
1: Ca + H2 ➜ , 2: Ca + Cl2
Answer: 737
737-861Calcium reacts with hydrogen at high temperature of form hydrides
1: Ca +H2 ➜ CaH2
Question: 738
Why the trend of electron affinity and electron -negativity same in the period?
Answer: 738
738-861The 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: 739
Which factors affect the non-metallic character ?
Answer: 739
739-861Non-metallic character depends upon Electron affinity and electronegativity
Question: 740
Is the Boyle's law valid at very high temperature?
Answer: 740
740-861No. Boyle's law is not valid at very high temperature
Question: 741
Write four physical properties of calcium metals .
Answer: 741
741-8611: Calcium is silvery grey and fairly harder metal
Question: 742
Why noble gases are not reactive ?
Answer: 742
742-861The 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: 743
Write the names of noble metals .
Answer: 743
743-861The metals which give least reactions are called noble metals
Question: 744
Define single covalent bond and give one example .
Answer: 744
744-861'When one electron is contributed by each bonded atom ,one bond pair is formed and it forms a single covalent bond '
Question: 745
Write down four important chemical properties of metals .
Answer: 745
745-8611: Metals easily lose electron and form positive ions
Na➜ Na +1 +le-
Question: 746
Differentiate between homoatomic and heteroatomic molecules with example.
Answer: 746
746-861Homoatomic molecules; A molecule containing same type of atoms is called monatomic molecule.
for example: H2, O3, S8
Question: 747
iodine exists in solid state, can it be beaten with hammer to form sheets?
Answer: 747
747-861No, only solid metals have the characteristic to be beaten with hammer to for sheet
Question: 748
Give example of two polar compounds and give their chemical formula .
Answer: 748
748-861Following are some examples of two polar compounds :
Question: 749
What is the trend of electronegativity in the period ?
Answer: 749
749-861The 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: 750
In which units body temperature is measured ?
Answer: 750
750-861Body 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: 751
Why HF is a weak acid ?
Answer: 751
751-861HF 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: 752
Complete and balance the given chemical equation Na + H2➜ ?
Answer: 752
752-8612Na + H2➜ 2NaH
(Sodium ) (Hydrogen ) (sodium hydroxide )
Question: 753
Convert the following. Ans: a) 70 cm lig to atm. b) 3.50atm to torr. c) 1.5 atm to Pa.
Answer: 753
753-86170 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: 754
Give application of silver ?
Answer: 754
754-8611: Compound of silver are widely used in photographic films
Question: 755
Define oxidation state ?
Answer: 755
755-861Oxidation state is the apparent charge assigned to an atom of an element in a molecule or ion
Question: 756
WHat do you know about the oxidizing characteristics of halogens ?
Answer: 756
756-861Chlorine 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: 757
Why nitrogen is necessary for safety of life on earth ?
Answer: 757
757-861Nitrigen 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: 758
Why ionization energies of alkaline earth metals are higher than alkali metals?
Answer: 758
758-861Alkaline 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: 759
Write two method for prevention of corrosion .
Answer: 759
759-861Method for prevention of corrosion:
Following are some method from avoiding corrosion
Question: 760
Why does evaporation increase with the increase of temperature?
Answer: 760
760-861At 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: 761
Which allotropic form of carbon is stable at room temperature (25°C)?
Answer: 761
761-861Graphite is more stable at room temperature
Question: 762
What do you mean by %volume/volume
Answer: 762
762-861It 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: 763
Complete and balance the following equation Mg +N2➜ ?
Answer: 763
763-8613Mg +N2➜ Mg3N2
(Magnesium ) (Nitrogen) (Magnesium nitride)
Question: 764
What do you mean by malleable and ductile ?
Answer: 764
764-861Malleability 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: 765
Why ionization energy ok alkaline earth metals is higher than alkali metals?
Answer: 765
765-861The size of alkali metals is samaller than alkaline earth metals that's why they have high ionization energy
Question: 766
Why amorphous solids do not have sharp melting points while crystalline solids do have ?
Answer: 766
766-861Amorphous 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: 767
Write down names of two very reactive metals .
Answer: 767
767-8611: Li (Lithium)
Question: 768
Is triple covalent bond stronger than double covalent bond ? Give reason
Answer: 768
768-861In 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: 769
Write two properties of silver
Answer: 769
769-8611: Silver is a white Lustrous metal
2: Silver is good conductor of heat and electricity
3: Silver is a very malleable and ductile
Question: 770
Why O2 is necessary for rusting ?
Answer: 770
770-861Rusting 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: 771
Why is the ionization energy of Na more than 'K'?
Answer: 771
771-861The 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: 772
Name a metal which can be cut with knife?
Answer: 772
772-861Sodium is that metal which can be cut with knife, because it is soft.
Question: 773
Justify with an example the solubility of salt increases with increase in temperature?
Answer: 773
773-861When 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: 774
Why does Aluminium not rust ? Explain
Answer: 774
774-861Aluminium 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: 775
Why does reactivity of metals increase down the group?
Answer: 775
775-861The 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: 776
Define halogens . give example .
Answer: 776
776-861Halogens : The element of group 17 called halogens
Example : Chlorine , Fluorine , Bromine etc
Question: 777
Differentiate between ionic bond and covalent bond .
Answer: 777
777-861Ionic 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: 778
Why is 02 necessary for rusting?
Answer: 778
778-86102 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: 779
Name the most abundant non- metal in earth's crust?
Answer: 779
779-861Oxygen has has the highest percentage in earth's crust 47% and oceans 86% but second highest percentage in atmosphere 21%
Question: 780
Why is HF a weak acid ?
Answer: 780
780-861HF less ionizes , hydrogen bond is present between its molecules . That is why it is a weak acid
Question: 781
Write two properties of non-polar covalent compounds .
Answer: 781
781-8611: They do not undergo charge separation
Question: 782
Why does chlorine accept an electron and attain -1 charge ?
Answer: 782
782-861Chlorine 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: 783
Which of the following will scatter light and why?
Sugar solution, Soap solution, Milk of magnesia.
Answer: 783
783-861Soap solution is colloidal solution and have particles large enough to scatter the light
Question: 784
Why an iron grill is painted frequently?
Answer: 784
784-861Iron 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: 785
How is platinum used as a catalyst in automobiles and what are advantages of this use?
Answer: 785
785-861An 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: 786
Why silver and gold are least reactive?
Answer: 786
786-861Silver 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: 787
How electroplating of zinc is carried out ?
Answer: 787
787-861The 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: 788
Can colloids he separated by filtration, if not why?
Answer: 788
788-861Colloids cannot be separated by filtration because particles are big but they can pass through a filter paper.
Question: 789
Why the boiling point of water higher than alcohol?
Answer: 789
789-861Water 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: 790
Write the redox reaction taking place during the electroplating of chromium .
Answer: 790
790-861Chromium 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: 791
In electroplating of silver , from which electrolyte Ag+ comes and where they deposit ?
Answer: 791
791-861In the electrolyte of silver (Ag)+ comes from anode and deposit on cathode .
Question: 792
How does nature of attractive forces of solute-solute solvent -solvent affect the solubility?
Answer: 792
792-861Solutions 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: 793
Give chemical reaction of H2 and Cl2 and l2Reaction of H2 with Cl2 :
Answer: 793
793-861H2 reacts with Cl2 only in the presence of sunlight
H2 + Cl2 ➜ 2HCL
Question: 794
What is electropositivity ? Explain with example
Answer: 794
794-861Electropositivity : 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: 795
Why copper is used for making electrical wires ?
Answer: 795
795-861Copper is used for making electrical wires because it is highly ductile and least reactive . Copper is among noble metals
Question: 796
Write any two uses of sodium .
Answer: 796
796-8611:Sodium potassium alloy is used as a coolant in nuclear reactor
Question: 797
What is meant by malleable and ductile metals ?
Answer: 797
797-861Malleable : The substance that can be drawn into sheets are called malleable
Question: 798
Write four physical properties of metals
Answer: 798
798-8611: Almost all metals are solid (Except mercury)
Question: 799
An element in oxidation state +7 gains electrons to be reduced to oxidation state +2 . How
Answer: 799
799-861Suppose an element X +7
Question: 800
Can pure gold be used for making ornaments ? If not , why ?
Answer: 800
800-861Gold 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: 801
Anode of downs cell is made up of non metal , what is its name ?
Answer: 801
801-861Anode of down cell is made of non-metal , Its name is graphite . The Cl- ions are oxidized to give Cl2 gas at anode
Question: 802
Metals are good conductors of electricity .Why ?
Answer: 802
802-861Metals have free moving electrons called mobile electrons . Due to presence of these electrons metals are good conductors of electricity
Question: 803
Why ionization energy of Na is less than Mg?
Answer: 803
803-861Ionization 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: 804
What is redox reaction ?
Answer: 804
804-861The reaction in which simultaneously oxidation and reduction takes place is called redox reaction
Question: 805
Write two properties of platinum.
Answer: 805
805-8611: Platinum is a noble metal and very least reactive
Question: 806
Why metallic character decrease along a period and increase in a group?
Answer: 806
806-861Along 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: 807
Write down the reaction of magnesium with oxygen . How oxygen reacts with magnesium ?
Answer: 807
807-861Magnesium reacts with oxygen and magnesium oxide is formed
Question: 808
Name the by-products produced in Nelson's Cell?
Answer: 808
808-861The chlorine and hydrogen gas are produce as by product in Nelson's Cell
Question: 809
Write down melting point and boiling point of sodium metal .
Answer: 809
809-861Melting and boiling point of sodium metal are as follows
Question: 810
Write down the name of four least reactive metals .
Answer: 810
810-861The names of least reactive metals are following
Question: 811
Write ant two chemical properties of non-metals .
Answer: 811
811-8611 : Non-metals usually do not react with water
2: They do not react with dilute acids because non-metals are itself electron acceptors
Question: 812
Why does oxygen molecule not form a polar covalent bond ?
Answer: 812
812-861In 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: 813
Write down names of any four halogens .
Answer: 813
813-8611: Fluorine 2: Chlorine 3: Bromine 4: Iodine
Question: 814
Which factor controls the non-metallic character of the element?
Answer: 814
814-861The non - metallic character of elements is depending upon the electron affinity and electron affinity and electronegativity
Question: 815
Write names of any two noble metals
Answer: 815
815-8611: Copper
Question: 816
In electroplating of silver , from which electrolyte Ag+ come or where they deposit ?
Answer: 816
816-861In the electrolyte of silver (Ag+) comes from anode and deposit on cathode
Question: 817
Why electro positivity decreases from left to right in a period?
Answer: 817
817-861Electropositivity 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: 818
Which compounds of halogens are stable ?
Answer: 818
818-861Halogens form very stable compounds with alkali metals
Question: 819
Write two uses of calcium .
Answer: 819
819-8611: It is used to remove sulphur from petroleum products
Question: 820
Name the metal which is the poorest conductor of heat ?
Answer: 820
820-861Lead is the poorest conductor of heat
Question: 821
Define polar covalent bond with example .
Answer: 821
821-861Polar 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: 822
Describe the chemical reaction of alkaline earth metals with hydrogen .
Answer: 822
822-861Alkaline 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: 823
Why the second ionization energy of magnesium is higher than the first one?
Answer: 823
823-861he 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: 824
What is the electronegativity of hydrogen and chlorine ?
Answer: 824
824-8611: Value of electronegativity of hydrogen (H) is 22
Question: 825
Give chemical reaction of methane with chlorine in bright light .
Answer: 825
825-861In bright light (sun light) Cl2 react with CH4 violently and explosively
Chemical reaction : CH4 +2Cl2 ➜ C+4HCL
Question: 826
Write down two properties of gold
Answer: 826
826-8611: Gold is a yellow sift metal
2: It is most malleable and ductile of all the metals
Question: 827
Ice floats on the surface of water . Give reason.
Answer: 827
827-861Floating 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: 828
What is the nature of metal oxide?
Answer: 828
828-861When metals react with oxygen they form metallic oxide, which are basic in nature. 2Mg+02➜2Mg0
Question: 829
What is the significance of water for survival of life .
Answer: 829
829-861Water 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: 830
State the physical properties of sodium .
Answer: 830
830-8611: Its melting point is 97°C
Question: 831
How electro positivity depends upon size and nuclear charge of an atom?
Answer: 831
831-861Electropositivity 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: 832
Describes the trends of electropositivity in a period and in a group .
Answer: 832
832-861Electropositive 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: 833
Why do non-metals accept electron readily ?
Answer: 833
833-861Non-metals have high electronegativity , can accept electrons readily in order to complete their last (valence ) shells
Question: 834
How will you compare he electropositivity ok alkali metals and alkaline earth metals ?
Answer: 834
834-861: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: 835
Can liquid and gases be brittle?
Answer: 835
835-861No, Only solid non-metals are brittle.
Question: 836
Why silver and gold are least reactive ?
Answer: 836
836-861From the transition metals of group 11 of periodic table Silover and Gold are least reactive because they do not lose electron easily
Question: 837
Write uses of silver .
Answer: 837
837-8611: 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: 838
Why is platinum is used to make jewelry ?
Answer: 838
838-861Platinum 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: 839
Why calcium is more electropositive than to magnesium?
Answer: 839
839-861Calcium 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: 840
In what conditions H2 reacts with l2 ? Give equation of the reaction .
Answer: 840
840-861H2 reacts with l2 on heating and in the presence of catalyst to produce hydrogen iodide
H2 + l2 ➜ 2Hl
Question: 841
Difference between oxidation state and valency
Answer: 841
841-861Oxidation : 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
Question: 842
Write two physical properties of non-metals.
Answer: 842
842-8611: Non-metals have less melting and boiling point (except diamond)
2: They are generally soft (except diamond)
Question: 843
Why sodium metal is more reactive than magnesium metal?
Answer: 843
843-861Sodium 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: 844
How platinum is used as a catalyst in automobiles and what are advantages of this use ?
Answer: 844
844-861Platinum alloyed with palladium and rhodium is used as a catalyst in automobile as catalyst converter . It converts harmful gases into harmless gases
Question: 845
Describe the non-metallic character in groups and period of a periodic table
Answer: 845
845-861Non-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: 846
Name the best ductile and malleable metal ?
Answer: 846
846-861Gold and silver
Question: 847
Why oxygen is called non-metal?
Answer: 847
847-861Non-metals form negative ions by gaining electrons. Oxygen atoms can accept 2 electrons therefore its valency is 2. 0+2e-➜0-2
Question: 848
Give chemical reaction between Methane (CH4) and chlorine (Cl2) in presence of diffused light .
Answer: 848
848-861CH4 + Cl2 ➜ CH3Cl +HCL
CH3Cl +Cl2 ➜ CH2Cl2+HCL
CH2Cl2 + Cl2 ➜ CHCl2 +HCL
CHCL3 + Cl2 ➜ CCl4 ➜ CCl4 +HCL
Question: 849
Why is gold used to make jewelry?
Answer: 849
849-861Gold 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: 850
Write chemical reaction of water with bromine .
Answer: 850
850-861bromine only reacts with water under following special condition .
Br2 + H2O ➜ HBr + HOBr
Question: 851
Write down names of any two moderate reactive metals
Answer: 851
851-8611: Magnesium
Question: 852
Why is 2nd ionization energy of magnesium very high than its 1st ionization energy
Answer: 852
852-861Second 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: 853
Differentiate between polar and non polar covalent bond .
Answer: 853
853-861Polar 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: 854
Why nitrogen forms compounds with alkaline earth metals directly ?
Answer: 854
854-861A alkaline earth metals from stable nitrides when heated with nitrogen
Question: 855
Why the second ionization energy of magnesium is higher than than first ?
Answer: 855
855-861Second 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: 856
What is difference between steel and stainless steel ?
Answer: 856
856-861Steel : Alloy of iron with other metals called steel
Question: 857
Why the ionization energy of Na is more than K?
Answer: 857
857-861Ionization 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: 858
Write down two significance of non-metals
Answer: 858
858-8611: 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: 859
Why valence of chlorine is 1 ?
Answer: 859
859-861The 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: 860
Why alkali metals are more reactive than alkaline earth metals ?
Answer: 860
860-861Alkali 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: 861
How chlorine chemical react with dilute ?
Answer: 861
861-861Chlorine react withcold dilute NaCl to give sodium hypochlorite
2NaOH +Cl2 ➜ NaCl +NaOCL + H2O
