give reason a gas exerts pressure on the walls of the container
Before we give the reason behind a gas exerts pressure on the walls of the container. First we will understand what kind of behaviour of the gas when it put into a closed packed container? How the increase of pressure in a container affect the gass's kinetic energy? What will happen inside a container?
So without any wasting time let's understand the it with the help of diagram.
As we can see in above diagram. There are total 4 piston filled with gasses molecules.
In piston A:- The gasses particles are less compressed so that the kinetic energy of the gasses particles has more to the compare of remaining pistons.
Due to the less in kinetic energy of gasses molecules. The pressure exerted from inside on the piston's wall is less to the compare of remaining pistons.
In piston B:- The gasses particles are more compressed so that the kinetic energy of the gasses particles has more to the compare of first piston 'A'.
Due to the more in kinetic energy of gasses molecules. The pressure exerted from inside on the piston's wall is more to the compare of first piston 'A'.
Conclusion
From the above experiment with piston and gases molecules we concluded that a more compressed gasses molecules exert high pressure on the walls of the container and a less compressed gasses molecules exert low pressure on the walls of the container.
From this experiment we also concluded that with pressure changes the behaviour of the gasses molecules also changes.
When we increase the compressibility of the container the pressure exerted on the walls of the container also increases due to the increasing of kinetic energy and vice-versa.