The word kina means motion and therefore the kinetic theory of matter explains many different properties of matter in terms of motion of the component particles called molecules. This theory was primarily developed by Maxwell-Boltzmann to explain the behavior of gases, but was later to other states of matter.
This theory assumes that gases are made of molecules, which are constantly in zigzag motion. During this motion, they strike each other and the walls of the container in which they are placed. Since the gas molecules are quite far apart from each other (there are considerable blank spaces between any two molecules), there is negligible attraction force between them gas. The force with which the molecules strike the container walls in a unit area is known as pressure.
If we compress a gas by applying more pressure, the volume decreases. Conversely, if we decrease the pressure, the volume increases. Thus in a way, more pressure means less volume and vice-versa. This is technically known as Boyle’s Law which says that if we keep temperature constant, the volume of a gas is inversely proportional to pressure.
or PV = Constant
Therefore, the product of the pressure and volume of any gas remains constant, if the temperature is constant.
The pressure of a gas remaining constant, the volume of a given mass of any gas is directly proportional to its absolute temperature temperature on the Kelvin Scale.