Question

define latent heat of fusion and latent heat of vapourisation

Answer 1

latent heat of fusion is the amount of energy required by the solid from surrounding to change it's state to liquid.
latent heat of vaporisation is the amount of heat energy required by the liquid from the surrounding to change into gaseous state..

Answer 2

latent heat of fusion :-
latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid at its melting point.

latent heat of vaporisation :-
latent heat of vaporization is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.