Question

What is meant by saying that latent heat of vaporization of water is 22.5*10 5 j /kg ??????

Answer 1

that the amount of heat required to turn 1kg of water into steam at a fixed temperature is this much.

Answer 2

Water in its initial state is present in liquid form but when it is heated the phase or the state of the water changes and gets converted into steam at a higher temperature than the initial temperature the water was having.

This change of phase of the water from liquid state to the steam is done with the help of a heat generation known as latent heat of vaporization. Here in the question it means $\bold{22.5 \times 10^{5} \mathrm{J} / \mathrm{kg}}$ of heat is required to change the water into steam.