A Gas Exerts Pressure On The Walls Of The Container. Particles of matter are constantly moving. When a molecule collides with the wall, they exert small force on the wall the pressure exerted by the gas.
This pressure is directly proportional to the temperature t of the gas.
Gas pressure is caused by the force exerted by gas molecules colliding with the surfaces of objects in fact, normal air pressure is strong enough to crush a metal container when not balanced by figure 1. The molecules are continually colliding with each other and with the walls of the container. Gas molecules collides with walls of vessels due to which there occurs change in momentum of molecules due to which force is produced and thus pressure. If one imagines the water frozen again at this point, then it becomes immediately clear that the walls obviously exert a supporting force and keep the frozen water in the container.