Materials : Metals And Non-Metals

Exercises 

1. Which of the following can be beaten into thin sheets?
(a) Zinc              (b) Phosphorus             (c) Sulphur                (d) Oxygen


2. Which of the following statements is correct?

(a) All metals are ductile.

(b) All non-metals are ductile.

(c) Generally, metals are ductile.

(d) Some non-metals are ductile.

Ans:-
(c) Generally, metals are ductile.


3. Fill in the blanks.

(a) Phosphorus is a very      reactive      non-metal.

(b) Metals are        good       conductors of heat and       electricity      .

(c) Iron is        more       reactive than copper.

(d) Metals react with acids to produce        hydrogen       gas.


4. Mark ‘T’ if the statement is true and ‘F’ if it is false.

(a) Generally, non-metals react with acids. ( F)

(b) Sodium is a very reactive metal.     ( T )   
   
(c) Copper displaces zinc from zinc sulphate solution.    ( F )

(d) Coal can be drawn into wires.   ( F )


5. Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.

Ans:-

6. Give reasons for the following.

(a) Aluminium foils are used to wrap food items.

Ans:-
Aluminium being a metal shows malleable as a property i.e it can be drawn into thin sheets. So, aluminium foils are used to wrap foods items.


(b) Immersion rods for heating liquids are made up of metallic substances.

Ans:-
Immersion rods for heating liquids are made up of metallic substances because iron being a metal is a good conductor of heat and electricity.


(c) Copper cannot displace zinc from its salt solution.

Ans:-
Copper cannot displace Zinc from its salt solution because copper is less reactive as compare to zinc and only a more reactive metal can displace the less reactive metal.


(d) Sodium and potassium are stored in kerosene.

Ans:-
Sodium and Potassium are stored in kerosene because they are very reactive metals, if gets in contact with air (atmospheric oxygen) catches fire. Also they reacts vigorously with water.


7. Can you store lemon pickle in an aluminium utensil? Explain.

Ans:-
Lemon pickle cannot be store in an aluminium utensil because lemon pickle contains acid which reacts with aluminum and thus liberate Hydrogen gas. Also, pickle will be spoil.


8. Match the substances given in Column A with their uses given in Column B.

Ans:-
(i) Gold - (d) Jewellery
(ii) Iron - (e) Machinery
(iii) Aluminium - (c) Wrapping food
(iv) Carbon - (f) Fuel
(v) Copper - (b) Electric wire
(vi) Mercury - (a) Thermometers


9. What happens when

(a) Dilute sulphuric acid is poured on a copper plate?

Ans:-
Copper doesn't react with dilute sulphuric acid, so no reaction would take place. But copper reacts when concentrated sulphuric acid is poured in copper plate and produces effervescence. Following reaction takes place :
       Cu(s)    +    conc. H2SO4(aq)   →    CuSO4(aq)   +      H2(g)


(b) Iron nails are placed in copper sulphate solution? Write word equations of the reactions involved.

Ans:-
When iron nails are placed in copper sulphate solution, iron being more reactive metal than copper, displaces copper from its salt solution. Following displacement reaction is carried out :
                  Fe(s)    +    CuSO4(aq)  →   FeSO4(aq)  +   Cu(s)


10. Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.

(a) How will she find the nature of the gas ?

Ans:-
In the gas containing test-tube, she should add few drops of water and cover it. Then shake the mixture well. After shaking the solution, test it with red-blue litmus paper. It will turn the blue litmus red showing its acidic nature.   

(b) Write down word equations of all the reactions taking place in this process.

Ans:-
(i) C(s)   +    O2(g)   →   CO2(g)↑
(ii) CO2(s)   +    H2O(l)   →   H2CO3(aq)

11. One day Reeta went to a jeweller’s shop with her mother. Her mother gave an old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?

Ans:-
There is a weight loss because for polishing the jewellary, it is dipped into a solution called Aqua Regia which contains HCl(hydrochloric acid) and HNO3 (nitric acid) in at a ratio of 3:1. Therefore, the outer layer of the jewellery gets dissolved in the solution and inner shinny layer appears.