Final answer:
Pressure exerted by a gas is directly proportional to the momentum of its molecules. Gas molecules impact the container walls, causing pressure through changes in momentum, which is governed by Newton's laws of motion.
Step-by-step explanation:
The pressure exerted by a gas is related to the momentum of its molecules on an atomic and molecular level. When gas molecules collide with the walls of a container, they exert force on the walls due to a change in momentum, resulting from Newton's second law which states that the rate of change of momentum is directly proportional to the applied force. This interaction of countless molecules colliding with the container walls results in the observable pressure of the gas.
In terms of Kinetic Theory, the pressure of a gas is directly proportional to the average kinetic energy of the molecules, which in turn depends on their velocity or momentum. Hence, as the momentum of the gas molecules increases (higher velocity or mass), so does the pressure. This is because more energetic collisions correspond to a greater change in momentum, equating to a larger force applied to the container walls over a given area.