Describe how gas particles behave when they collide with the walls of their container.

Gas particles move in constant random motion and collide with the walls of their container. These collisions exert a force on the walls, which is responsible for the pressure exerted by the gas.

Definition lens: Give the precise definition, then add a context sentence that shows how it is used. This question asks: Describe how gas particles behave when they collide with the walls of their container. The correct response is Gas particles move in constant random motion and collide with the walls of their container. These collisions exert a force on the walls, which is responsible for the pressure exerted by the gas., because gas pressure comes from particle collisions with container walls. In Particle motion in gases, the marking point should connect directly to explain that gas particles collide with each other and with the walls of their container. If the question includes values, the working must keep the appropriate unit and operation; if it is an explanation, it must name the relevant particle behaviour or energy change. This item belongs to Particle model and pressure, so avoid answers that switch to a different quantity, confuse heat with temperature, or describe gas pressure without collisions when collisions are the reason. Checkpoint 462 is distinct because it uses this exact question context and the definition lens rather than a generic particle-model sentence.