Question

why sodium and potassium are kept in kerosene

Answer 1

as Na and k are highly reactive and they even react vigorously with air and water

Answer 2

Sodium and Potassium are kept in kerosene. This is because they are highly reactive and thus catch fire when they are exposed into the atmosphere.

Sodium and Potassium react with water molecules in air to catch fire. Hence they are not advised to be stored in water. Hence they are stored in kerosene.