9th Class Chemistry Chapter 8 Short Questions with Answers Solved

Question: 1

Why Calcium is more electropositive than to magnesium?

Answer: 1

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Calcium is more Electropositive than magnesium metallic character or electropositive character or electropositive character down the group increases due to loosely held and can be easily with drawn from their shells.

Question: 2

How oxygen reacts with group II A metals?

Answer: 2

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They are less reactive towards oxygen and oxides are formed on heating.

Question: 3

Which group of metals is highly reactive?

Answer: 3

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Lithium, sodium, potassium, rubidium, cesium and francium, are highly reactive in nature. They are called alkali metals.

Question: 4

Why copper is used for making electrical wires?

Answer: 4

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Copper is used for making of electrical wires because copper is a good conductor of electricity and it is also ductile in nature as it can be easily drawn out into wires.

Question: 5

What is relationship between electropositivity and ionization energy.

Answer: 5

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Electropositivity depends upon the ionization energy which in turn depends upon size and nuclear charge of the atom. Small sized atoms with high nuclear charge have high ionization energy. Atoms having high ionization energy are less electropositive or metallic

Question: 6

What do you mean by metallic character?

Answer: 6

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Metallic character:Metals have the tendency to lose their valence electrons. This property of a metal is termed as metallic character or electro-positivity.

Question: 7

Why nitrogen forms compounds with alkaline earth metals directly?

Answer: 7

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A alkaline earth metals form stable nitrides when heated with nitrogen.

Question: 8

What type of elements are metals?

Answer: 8

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"Metals are the elements which are electropositive and form cautions by losing electrons. Example: Sodium, Potassium,Calcium

Question: 9

Why silver and gold are least reactive?

Answer: 9

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Silver 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: 10

What do you mean by 24 carat gold?

Answer: 10

10-42

Purity 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 all the part of alloy are gold.

Question: 11

Why Magnesium is harder than sodium?

Answer: 11

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Magnesium 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: 12

Why the oxygen is called non-metal ?

Answer: 12

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Nonmetals form regativeions by gaining electrons. On the way nonmetals are electronagative in nature and form acidic oxides.

Question: 13

How platinum is used as a catalyst in automobiles and what are advantages of this use?

Answer: 13

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Platinum alloyed with palladium and rhodium is used as catalyst in automobile as catalytic converter. It coverts harmful gases into harmless gases.

Question: 14

Name a metal which can be cut with knife/

Answer: 14

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Sodium is that metal which can be cut with knife, because it is soft.

Question: 15

Define Non -Metal.

Answer: 15

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Non-metals are usually non-flexible on heating. The are easily cut and break.

Question: 16

Name the most abundant non-metal in earth's crust?

Answer: 16

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Oxygen has the highest percentage in earth's crust 47% and oceans 80% but second highest percentage in atmosphere 21%

Question: 17

Define transition elements?

Answer: 17

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Each period consists of ten groups starting from group 3 to group 12. These are called transition metals.

Question: 18

Why HF is a weak acid?

Answer: 18

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HF is 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 readily ionized in water but HF+ does not easily ionized in water.

Question: 19

Write two uses of silver.

Answer: 19

19-42

1-Alloys of silver with copper are widely used in making coins, silverware and ornaments

2- Compounds of silvers are widely used in photographic filmsand dental preparations

Question: 20

What is the relationship between electro positivity and ionization energy

Answer: 20

20-42

Electropositive character of element depends upon the ionization energy of their atoms Atoms having high ionization energy are less electropositiveor shows less metallic character.

so small size atoms with ahigh nuclear charge have high ionization energy and low electropositivecharacters

Question: 21

What is the difference between steel and stainless steel?

Answer: 21

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Steel is a mixture while stainless steel is an alloy.

Question: 22

Write down the use of Sodium?

Answer: 22

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1- Sodium-potassium allay is used as a coolant in nuclear reactors.

2- It is used to produce yellow light in sodium vapour lamps

Question: 23

Why gold is used to make jewelry?

Answer: 23

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Platinum is used to make jewelry items because of itsunique characteristicslike color, beauty, strength, flexibility and resistance to ternish.

Question: 24

Difference between Steel and Stainless steel?

Answer: 24

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Steel: Steel is an alloy of iron, manganese, cobalt, chromium and 4 percent carbon. Stainless steel.The best example of alloying is stainless steel. Which is good combination of iron, chromium and nickel

Question: 25

State physical properties of metals ?

Answer: 25

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1-Almost all metals are solid

2- They have high melting and boiling point

3- They possess metallic luster and can be polished

Question: 26

Define Metal.

Answer: 26

26-42

On heating metals usually become soft and flexible. The are difficult to cut.

Question: 27

Write down uses of Magnesium?

Answer: 27

27-42

1- Magnesium is used in flashlight bulbs and in fireworks

2- It is used in the manufacture of light alloys

Question: 28

Which compounds of halogens are stable?

Answer: 28

28-42

Halogens form very stable compounds with alkali metals.

Question: 29

Why is HF weak acid?

Answer: 29

29-42

HF is a weak acid due to strong hydrogen bonding. Because partial positively charged h atom is entrapped between two strong

Question: 30

What are halogens?

Answer: 30

30-42

In periodic table element of group -17 consists of fluorine, chlorine , bromine, iodine and a stativeare called halogens

Question: 31

Difference between Metal and Non-metal?

Answer: 31

31-42

METALs

1-Metals easily loss electrons and form positive ions

2-They usually from ionic,compounds with non-metals

Question: 32

Write two uses of platinum?

Answer: 32

32-42

1- Platinum is used to make jewelry items.

2- is also used for production of hard disk drive coatings and fiber optic cable

Question: 33

What do you mean by 24 carats of Gold?

Answer: 33

33-42

Purity of gold is shown by carats that indicates the number of parts by weight of gold that is present in 24 parts of alloy

Question: 34

Which group of metals is highly reactive ?

Answer: 34

34-42

Group -1 are highly reactive elements in periodic shell electronic configuration . As there in only one electron in their valence shell.

Question: 35

Write any two chemical properties of metal.

Answer: 35

35-42

1-They have metallic bonding

2-They usually form ionic compounds with non-metals

Question: 36

Compare the chemical properties of Alkali and Alkaline earth metals.

Answer: 36

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Alkali Metals:

1- They are very reactive and always occur in combined form

2- Electropositivity These are highly electropostive

Question: 37

Why copper is used for making electrical wire ?

Answer: 37

37-42

Metals are malleable and ductile copper is a metal which in ductile and can conduct electricity easily, So copper is used for making electrical wires:

Question: 38

Define electro positivecharacter?

Answer: 38

38-42

The tendency of an element to closeone or more electrons to form a positive ion is called electro positivecharacter or electro positivity.

Question: 39

Writes two uses of calcium?

Answer: 39

39-42

1- It is used to remove sulphur from petroleum products

2- It is used as reducing agent to produceCr, U and Zr

Question: 40

Why silver is not used in pure form?

Answer: 40

40-42

Because the demand of silver for industrial purpose, etc thatswhy silver istoused in pure form

Question: 41

What do you mean by malleableand ductile?

Answer: 41

41-42

Malleable:

The property of metals that it can be converted into sheets is called as malleability

Question: 42

Write down the trends of electropositivecharacter in periodic table?

Answer: 42

42-42

Decreases across the period from left to right in periodic table because size of nuclear charge.

Chemistry Chapters

9th Class Chapter 8 Chemistry Short Questions

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