Question

White Phosphorus is generally kept under :

• A. Alcohol
• B. Water
• C. Glycerine
• D. Kerosine oil
• E. Ether

Answer 1

Answer: (B)

The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in $P_4$ molecule where the angles are only ${60}^0$ It readily catches fire in air to give dense white fumes of $P_4{O}_{10}$.

$P_4+5O_2\to P_4{O}_{10}$
Therefore it is kept in water to avoid oxidation by the oxygen present in air. It is kept in water because it is insoluble in water.

So answer is B.