In the free state, water occurs in the solid, liquid and gaseous states.

1. Solid state: A large amount of fresh water is found in the form of snow or ice.
2. Liquid state: Most of the water present in oceans and found in streams, rivers, lakes, ponds and springs on land is water in the liquid state.
3. Gaseous state: Water vapour present in the air is in the gaseous state. Water vapour condenses in the sky to form clouds. Mist and fog are also examples of water in the gaseous form.

Water is considered a compound because it is made of two elements hydrogen and oxygen combined in the ratio 1:8 by mass.

Mass ratio of elements H₂O

 H : O, 2 × 1 : 16 × 1 = 1 : 8

(Atomic mass of H = 1, O = 16)

Components of water cannot be separated by physical methods but can be separated by electrolysis of water. 

a) The temperature in Mumbai and Chennai do not fall as low as in Delhi because these cities are situated in the coastal areas. Due to high specific heat capacity, the presence of a large amount of water is able to modify the climate of the nearby land areas making them warmer in winter and cooler in summer. So, the temperature does not fall as low as it does in Delhi.

b) Our body is almost 65% of water, and it has the property of specific heat. Due to high specific heat capacity, the presence of a large amount of water is able to modify the climate of the body and control the temperature of our body, which is warm in winter and cool in summer.

Water dissolves many substances forming an aqueous solution. It can dissolve solids, liquids and gases. When a solid dissolves in water, the solid is the solute, the water is the solvent and the resultant liquid is the solution. So, it is said that water is a universal solvent. In other words, water can dissolve nearly every substance.