What happens to the frequency of particle collisions with the walls of a container when the volume of a fixed mass of gas decreases (Pressure in gases (physics only))

The correct answer is The frequency of collisions increases.

Unit lens: Check the units before giving the final statement so the physics quantity is not swapped. This question asks: What happens to the frequency of particle collisions with the walls of a container when the volume of a fixed mass of gas decreases (Pressure in gases (physics only)). The correct response is The frequency of collisions increases, because density links mass and volume, so the answer must preserve which quantity is being calculated. In Pressure in gases (physics only), the marking point should connect directly to (Physics only) Explain how changing the volume of a fixed mass of gas changes the frequency of particle collisions with container walls. 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 517 is distinct because it uses this exact question context and the unit lens rather than a generic particle-model sentence.