An element 'X' is a poor conductor of electricity. It burns in oxygen to produce a gas which dissolves in water, and the resulting solution turns blue litmus paper red. The element 'X' is:

Consider the following assertion and reason: Assertion (A): White phosphorus is stored under water. Reason (R): It is highly reactive and catches fire spontaneously when exposed to air. Select the correct option:

White phosphorus is highly reactive and stored under water in laboratories primarily to: