The kinetic-molecular theory of gases can be stated as four postulates:
1.A gas consists of molecules in constant random motion.
2.Gas molecules influence each other only by collision; they exert no other forces on each other. They do not stick to each other.
3.All collisions between gas molecules are perfectly elastic; all kinetic energy is conserved. When cars collide, energy is lost to bending bumpers and metal. Molecules do not act like this. Instead they act like billiard balls. Billiard balls do not lose energy when they collide.
4.The volume actually occupied by the molecules of a gas is negligibly small; the vast majority of the volume of the gas is empty space through which the gas molecules are moving.