Question

with the help of an experiment prove that the atmosphere contain water vapour​

Answer 1

Here is an experiment to prove that water vapour is present in the air,

Use a humidity meter at a beach you will see that the air has a lot of water vapour and do the same in an inland area the reading will be lesser compared to the beach. This is because the water from the sea evaporates and the water vapour is higher and vise-versa.