Kinetic Molecular Theory of Gases:

The kinetic molecular theory of gases explains the physical behaviour of gases.

Main Principles of Kinetic Theory of Gases:

It has the following main principles or postulates.

All gases consist of molecules which are widely separated from each other.
Space occupied by gas molecules is negligible as compared to space among gas molecules. i.e. the volume of gas molecules is negligible as compared to the volume of the gas.
The gas molecules are in constant and random motion, while doing so they collide with each other as well as with a wall of the container.
Gases exert pressure due to the collision of their molecules with the wall of the container.
Gas molecules make elastic collisions.
No forces of attraction among gas molecules exist.
The average kinetic energy of gas molecules is directly proportional to absolute temperature
Av. K.E α T
Two gases at the same temperature have equal average kinetic energy.
Gravity has no influence on gas molecules.