Water exists in all the three states. Discuss.

Water exists in all the three physical states : as solid (ice), as liquid (water) and as gas (water vapour). It occurs in both free as well as combined states.

Occurrence of water in free state:

• Solid state — In the form of ice, snow, frost.
• Liquid State —
  • On the earth's surface as river, water, lake water, sea water, spring water.
  • Below the earth's surface in well water and moisture accumulation in the soil.
  • Above the earth's crust as dew.
• Gaseous state [vapour] — as water vapour, clouds, mist, fog.

Occurrence of water in combined state :

• Water occurs in the combined form in all living matter i.e., plants and animals.
• Water is present in hydrated salts e.g., MgCl₂.6H₂O and in certain minerals.
• Earth's surface - Covers nearly 75% of earth's surface.
• Human body - Nearly, 70% of the body weight.
• Food products - Green vegetables [80-90%], Milk [80-85%], Dry cereals [3-5%]