Question

why lithium is stored in paraffin wax, not in kerosene ?

Answer 1

as lithium has lesser density than kerosene it floats on top of it so paraffin wax is used to store lithium

Answer 2

Lithium can not be stored in kerosene as it floats on the surface of kerosene because of its low density. Therefore, lithium is generally kept /wrapped in paraffin wax.