Question

How boiling of water is a physical change as it changes into vapour ???

Answer 1

Well if you trap vapour in a glass lid it again condenses to for water which is the previous state so, its a physical change.

Answer 2

it will certainly change into vapour state but it can again be brought back into its water state
as for eg
when u boil the water on a gas the the water changes into vapour state but when u put a plate on it u will she that it has tiny droplets of water that is what is being interchanged