Question

Explain by activity that air contains moisture

Answer 1

If u keep an unhydrated salt outside it will become hydrated

Answer 2

Take a glass vessel which is absolutely dry on the outside.Put some ice cubes in it.Within a short time you will observe that tiny droplets of a colorless liquid get condensed on the outside surface.This occurs the air layer touching the outer surface of the vessel becomes very cold and condenses the water vapor in it to droplets.So that's why the air contains moisture.