Question

(1)
(iv)
Hydrogen gas is HOLLUM
Calcium does not occur in free state in nature.
Sodium or potassium metals are kept immersed under kerosene​

Answer 1

Answer:

DETAILED EXPLANATION GIVEN BELOW

Explanation:

ii ] Metals of high reactivity are never found in free state. They are always combined with impurities. Answer: Calcium cannot exist in its natural state since it's highly reactive and readily reacts with the surrounding elements to form Calcium compounds

iii] Sodium and Potassium are kept in kerosene because they are very reactive. If kept freely in contact with air or water they might explode or catch fire which is extremely dangerous. ... If it is kept in open it can explosively react with oxygen to catch fire.

Answer 2

-Sodium is a very reactive metal. It is kept in kerosene to prevent it from coming in contact with oxygen and moisture. If this happens, it will react with the moisture present in air and form sodium hydroxide which is a highly exothermic reaction.