• # question_answer Out of dry air and wet air, which is heavier?

Dry air mainly contains gases like nitrogen and oxygen along with small proportions of the other gases. The wet air on the other hand, also contains a small amount of water vapours. Now, vapour density of water vapours is less than that of nitrogen and oxygen because molar mass of ${{H}_{2}}O$ (18) is less than that of ${{N}_{2}}$(28) and ${{O}_{2}}$ (32). This means that heavier molecules of nitrogen and oxygen have been replaced by lighter molecules of water vapours when the dry air changes to wet air. Therefore, dry air is heavier than wet air.