Question

State three differences between water and air.

Answer 1

Water:

1. The components of water are hydrogen and oxygen which are chemically combined in a fixed ratio of 1 : 8 by mass.
2. The chemical composition of water remains the same from whatever source it is obtained.
3. The properties of water are completely different from the properties of elements from which it is formed i.e. hydrogen and oxygen.
4. Energy change occurs in the formation of water.
5. A molecule of water is represented by a definite formula H₂O.

Air:

1. The main components of air are nitrogen, oxygen, carbon -dioxide, water vapour which are not chemically combined.
2. The composition of air varies from place to place. During the rainy season, the air becomes humid due to the presence of more water vapour. Some impurities like sulphur dioxide, hydrogen sulphide etc. also changes its composition at some places.
3. The components of air retain their individual properties but not air.
4. No energy change occurs when components of air are mixed together.
5. Air cannot be represented by any chemical formula.