Q61 of 102 Page 77

Why is phosphorus kept under water?

Metals react with water to produce hydrogen gas. Phosphorus cannot be kept open in the air because it combines with oxygen so easily that it catches fire automatically. For safety, phosphorus is stored under water in chemical laboratories.


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60

Give reasons for the following:

(a) Sodium and potassium are stored in kerosene.


(b) Copper cannot displace zinc from its salt solution (zinc sulphate solution).

 61

Why are metals used for making bells?

 62

Which of the following can be beaten into thin sheets? Why?

(a) Zinc


(p) Phosphorus


(c)Sulphur


(d) Oxygen

 63

Match the substances given in column A with their uses given in column B:

Column A


(i) Gold


(ii) Iron


(iii) Aluminium


(iv) Carbon


(v) Copper


(vi) Mercury


Column B


(a) Thermometers


(b) Electric wires


(c) Wrapping food


(d) Jewellery


(e) Machinery


(f) Fuel