Question

a gas exerts pressure on the walls on the container

Answer 1

<>The particles of Gas are moving constantly in all directions
<>While they move , they come in contact with other particles and collide with each other
<>So , they also exert pressure on the walls of the container

Answer 2

Gases are the state of matter where molecules are packed very loosely. They move very freely . When they are kept in a container also these particles move freely and hit the walls of the container thereby exerting some amount of force on it.

hope it helps u.....