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).

(a) Both Sodium and potassium are highly reactive metals. They can react with the moisture present in air. The reaction of sodium and potassium with water is highly exothermic in nature. It produces a lot of heat energy and this heat energy can cause the hydrogen gas produced during the reaction, to catch fire. In order to keep it safe, sodium and potassium are stored in kerosene.

(b) Copper cannot displace zinc from zinc sulphate solution as zinc is more reactive than copper and is also placed above copper in reactivity series of metal.