Question

Give reason why gases exert pressure on the walls of the container vessel

Answer 1

Every thing on earth that has weight exerts pressure.
So gases do exert pressure as well. Gases exert pressure on everything they surround. They exert pressure on our body too. So the inside air exerts pressure on the walls to come out but the outside air balances the pressure.

Answer 2

Gas is a state of particles. In this particular state,the molecules will be having higher energy. As energy increases, the motion of particles will increase. Because of this the particles in gaseous state will be in continuous motion. Because of this continuous zig zag motion, the particles will collide with themselves and with the walls of the container, when the gas is kept in a closed container. This collision will exert a pressure on the walls