Question

A gas can exert pressure on walls of the coantainer .assign region

Answer 1

Particles of gases collide against the walls of the containing vessel and impact momentum to them this is responsible for the pressure of gas.

Answer 2

Because in the gaseous state, the particles move about randomly at high speed. Due to this random movement, the particles hit each other and also the walls of the container. The pressure exerted by the gas is because of this force exerted by gas particles per unit area on the walls of the container.