Question

how will you demonstrate that water vapour is present in air

Answer 1

AIM: to prove that water vapour is present in air
MATERIALS REQUIRED: ice cubes/cold water, a glass
PROCEDURE: put the ice cubes or cold water in the glass
OBSERVATION: tiny water droplets are seen on the outer surface of the glass
INFERENCE: water vapour is present in the air
REASON: the gaseous water vapor when comes in contact with the cold surface of the glass, it condenses and forms water droplets

Answer 2

take a glass and pour cold water .
then we see the small drop of water
on the outer side the glass.
when we pour cold water in the glass
water vapour in the air is convert in liquid .
hense, we demostrate the water vapour present in air