Question

The pressure of a gas is caused by

Answer 1

The rapid motion and collisions of molecules with the walls of the container causes pressure.

Answer 2

Answer:

The rapid motion and collisions of molecules with the walls of the container causes pressure (force on a unit area). Pressure is proportional to the number of molecular collisions and the force of the collisions in a particular area. The more collisions of gas molecules with the walls, the higher the pressure.

(Don't know for sure but...)