Class8.L-3. Metals and Non-metals

EXERCISE

A. Choose the correct option for each of the following.

1.Metal + dilute acids→ salt + Hydrogen gas  (option .b)

2.Identify the correct increasing order of reactivity of the given metal.

ANS:- a)Cu<Zn<Mg

3.The metal that is very soft and can be cut with knife is

ANS:-  c)Sodium

4.The non-metal that is a good conductor of electricity is

ANS:- c)Graphite (Carbon)

5.Which of the following metals reacts vigorously with water?

ANS:- c)Potassium

B. State whether the following statements are True (T) or False (F) .

1.Most metals are not sonorous. (T)

2.Non-metals are generally soft except diamond. (T)

3.Non-metals are good conductors of electricity except

carbon. (F)

4.Highly reactive metals displace less reactive metals from their salt solution. (T)

C. Fill in the blanks with the correct words.

1.The property by which substances can be beaten into thin sheet is called-Malleability  .

2.The property by which substances can be drawn into thin wire is called-Ductility .

3.The metal present at the top of the activity series i-Potassium.

4.Metallic oxides are - basic in nature .

5.The element that does not react with water under any condition is- gold .

D. Name the following.

1. A metal that is liquid at room temperature→ Mercury .

2.A metal that is stored in kerosene→ Sodium .

3.The non-metal that is used as a disinfectant →Chlorine .

4.The process of coating iron objects with zinc→Galvaniztion .

5.The black substance formed due to corrosion of silver

→ Silversulphide .

E. Answer the following questions briefly.

1.Write any two properties of metals.

ANS:- 

Two properties of metal are-

a) They are generally solid at room temperature and

crystalline in nature.

b)They are shiny (Lustre) in appearance.

2.What are displacement reaction?

ANS:- 

The reactions in which metals react with a salt solution and 

displace or replace the metal present in the salt solution are 

known as displacement reaction.

3.What is corrosion?

 ANS:- 

The process in which atmospheric moisture and gases slowly eat away the surface of metals is  known as corrosion.

4.What is the significance of activity series of metals?

ANS:- 

The significant of activity series is that the metal placed higher in 

the series are more reactive than those placed below them .

5.What is the difference between ductility and sonority?

ANS:-

Ductility	Sonority
1)It is a property by which substances can be drawn into thin wires.	1)It is property by which substances can produce a ringing sound when they are struck with a hard object.

F. Answer the following questions in details.

1.Distinguish between the physical properties of metals and non-metals.

ANS:-

Metal	Non-metal
1)They are generally solid at room temperature  and crystalline in nature. 2)They are shiny in appearance. 3)Metals are hard. 4)They are good conductor of electricity. 5)Most metal are ductile. 6)They are malleable and not  very  brittle.	1)They exit in solid or gaseous state at room temperature . 2)They are not shiny in appearance . 3)Non-metals are soft. 4)They are bad conductor of electricity. 5)Non-metals are non-ductile. 6)Most of them are brittle but not malleable.

2.Describe briefly the chemical properties of metals with the

 help of examples.

ANS:-

Some chemical properties of metals 
given below-

a)Reaction with oxygen:When metals react with oxygen they form 
metallic oxides which are basic in nature.

     

b)Reaction with water: Metals react with water to form metal oxides or metal hydroxides and hydrogen gas.

c)Reaction with Acids: Metals react with acid to form salt and release hydrogen gas .

3.List the uses of any five metals.

ANS:-

a)Copper: 

It is used in making of electrical appliances, wires

and cable ,boiler pipes etc.

b)Iron: 

It is used in the making of water pipes, railing, nuts,

bolts ,tools etc.

c) Aluminium: 

Used for making high-voltage electronic wire,

utensils.

d)Magnesium: 

It is used in fireworks.

e)Zinc:

 It used in galvanized iron pipes , dry cells.

4.Describe the uses of any five  non-metals.

ANS:-

a)Chlorine: 

It is used as a disinfectant to sterilize water .

b)Iodine: 

It is used in preparation of tincture iodine and

iodized salt.

c)Helium:

 Used for filling balloons.

d)Phosphorus: 

Used in the manufacture of matchstick,

fertilizer, fireworks etc.

e)Graphite: 

Used for making electrodes in dry cells, lead in

pencils, dry lubricant .

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