Question

how the plants add water vapour in air plz any one can say this and

Answer 1

because the plants will absorb water after the about the heat of sun the water will be change into water vapour

Answer 2

$\huge\color{Pink}{Hey\: Mate!!}$

here is your answer:

Plants add water vapour into the air by the process of transpiration. In this process they release the excess of water through pores on their leaves.

Hope it helps you!!

$\boxed{Thankyou!!}$