A sealed container holds a fixed mass of gas at a constant temperature. If the volume of the container is halved, what happens to the gas pressure and why, according to the particle‑model?

The gas pressure doubles. Halving the volume brings the gas particles closer together, so they collide more frequently with the walls and with each other. The increased collision frequency and force raises the pressure, as described by the particle‑model.

Practical lens: Link apparatus, readings, and uncertainty to the exact measurement named in the objective. This question asks: A sealed container holds a fixed mass of gas at a constant temperature. If the volume of the container is halved, what happens to the gas pressure and why, according to the particle‑model. The correct response is The gas pressure doubles. Halving the volume brings the gas particles closer together, so they collide more frequently with the walls and with each other. The increased collision frequency and force raises the pressure, as described by the particle‑model., because gas pressure comes from particle collisions with container walls. In Particle motion in gases, the marking point should connect directly to distinguish gas pressure from atmospheric pressure in particle-model explanations. 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 506 is distinct because it uses this exact question context and the practical lens rather than a generic particle-model sentence.