Question

explain what do you understand by following diagram?

Answer 1

This diagram represents the following things:-
the amount of heat energy required in change of a solid to liquid is called latent heat of fusion.
..........in change of liquid to gas is called latent heat of vaporisation.
..........in change of gas to liquid is called latent heat of condensation.
..........in change of liquid to solid is called latent heat of solidification.

Answer 2

Answer:

Transitions between solid, liquid and gaseous phases involve a specific amount of latent heat absorbed or released.  

If heat is added at a constant rate to mass of solid-like ice to take it to liquid water, it is called latent heat of fusion and the heat required to convert liquid to gas is latent heat of vaporization.  

In the phase change from gas to liquid releases latent heat of condensation and from this phase change of liquid to solid releases latent heat of freezing.