Give the assumptions of the kinetic molecular theory.

The assumptions of the kinetic molecular theory are :

1. Composition of gases — Gases are made of tiny particles moving in all possible directions at all possible speeds. The molecules are negligibly small as compared to the volume of the occupied gas.
2. Gases have neither a fixed volume nor a fixed shape — There is negligible force of attraction between the particles (gas molecules). Therefore, the particles (gas molecules) are free to move in the entire space available to them. Their movement is only restricted by the container, hence it takes the shape of the container.
3. Gases exert pressure in all directions — The moving particles of gas collide with each other and with the walls of the container. Due to these collisions, gas molecules exert pressure. It has been found, that at a given temperature, time and area, the same number of molecules of a gas strike against the walls of the container. Thus, gases exert the same pressure in all directions.
4. Gases are highly compressible — There are large inter-particle (inter-molecular) space between gas molecules, and this accounts for high compressibility of gases.
5. Gases are highly expansible — Gases increase in volume with a decrease in pressure and an increase in temperature.
6. Gases have low density — The number of molecules per unit volume in a gas is very small due to the large intermolecular spaces between their molecules. Therefore, gases have very low density.
7. Gases have a natural tendency for diffusion — Due to large intermolecular spaces, the molecules of two gases mix with each other in such a manner that a homogeneous gaseous mixture is formed.
8. Gases can be liquefied — On cooling, the kinetic energy of the molecules of a gas is reduced and on applying pressure on a cooled gas, the molecules come closer. Thus, the gas liquefies.