With the help of an activity show that air contains water vapours.

Explanation

In a tumbler made up of steel, take crushed ice. Completely dry it from outside with a towel. Allow the tumbler to stand for about ten minutes. Drops of water will be seen deposited on the outer walls of the tumbler.
Explanation. Air contains in it a very small percent of water as vapours. These pass into the atmosphere as a result of evaporation which is taking place from water present in ponds, rivers, lakes, oceans etc. When these water vapours present in air come in contact with outer surface of steel tumbler, they condense because of the presence of ice inside it. The drops of water thus formed appear on the outer walls of the tumbler.