Question

why gas exerts pressureon the wall of the container​

Answer 1

Because the molecules are continually colliding with each other and with the walls of the container. When a molecule collides with the wall, they exert small force on the wall The pressure exerted by the gas is due to the sum of all these collision forces

Answer 2

gas exerts pressure on the walls of the container because of high kinetic energy which wants the gas to expand out of the container due to which the particles of the gas exert pressure on the walls of the container