Is pressure caused by the collision of gas molecules with their surroundings?
Molecules of gas are always in random motion within the container. The gas molecules undergo frequent & consistent collisions with other molecules as well as the wall of container.
The collisions result in the momentum exchange with the container wall & the rate of change of momentum results in the force exerted by gas molecule on the container wall. This force per unit area exerted by gas molecules is called pressure.
Thus, pressure of gas is caused by the collisions of gas molecules