Consider some amount of gas in a container, these gases will be moving randomly in all the direction with all possible velocities, also these gas molecules. acquire kinetic energy based on their velocities. In order to explain this observed behavior of gases, Bernoulli proposed a model called Kinetic Theory of Gas . . Gases consist of atoms and molecules moving ceaselessly and randomly with all possible velocities in all directions. Each of these gas particles has certain amount of kinetic energy that depends upon it is temperature. Lighter particles move faster than heavier ones at all temperatures. Careful observations show that smaller the particles, more rapid is their motion at a given temperature .