The main assumptions of kinetic theory of gases are :

1. A gas is made up of a large number of sub-microscopic particles called atoms.
2. Gases consist of particles in constant random motion. They continue to move in a straight line until they collide with each other on the walls of their container.
3. Gas pressure is due to the moleiMIeS colliding with the walls of the container. All of these collisions are perfectly elastic. This means that there is no change in energy of either the particles or the wall upon collision. So, no energy is lost or gained from collisions.
4. No molecular forces are at work. The potential energy of molecules is zero. So, whole of the energy. in an ideal gas is kinetic energy only. There is no attraction or repulsion between the particles.
5. The time taken for the collision is negligible as compared with the time between collisions.
6. The kinetic energy of a gas is a measure of its kelvin temperature. Each gas molecule has different speed but the temperature and kinetic energy of gas refer to the average of these speeds.
7. The average kinetic energy of an atom of gas is directly proportional to the temperature. An increase in temperature increases the speed in which the gas molecules move.
8. All gases at a given temperature have same average kinetic energy.
9. fighter molecules of a gas move faster than the heavier molecules.