What happens when gas particles collide with the walls of their container?

The correct answer is They exert a force on the walls..

Particle lens: Describe arrangement, motion, spacing, collisions, or energy changes only when they are relevant here. This question asks: What happens when gas particles collide with the walls of their container. The correct response is They exert a force on the walls., 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 456 is distinct because it uses this exact question context and the particle lens rather than a generic particle-model sentence.