Question

phosphorus is always kept in water. Why? ​

Answer 1

Hello mate..
It readily catches fire in Air to give dense white fumes of P4O10. Therefore it is kept in water to avoid Oxidation by the Oxygen present in the Air. Phosphorus is insoluble in water. ... White phosphorus spontaneously reacts with oxygen in the air to burst into flame and burn itself into phosphorus pentoxide.

Answer 2

Phosphorus is stored in water because phosphorus is very reactive non metal. It catches fire if exposed to air. To prevent the contact of phosphorus with atmospheric oxygen,it is stored in water.

I hope that this will help you