What happens to the pressure of a gas when its volume decreases at constant temperature (Pressure in gases (physics only))

The correct answer is The pressure 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 pressure of a gas when its volume decreases at constant temperature (Pressure in gases (physics only)). The correct response is The pressure 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) Apply the relationship pressure x volume = constant for a fixed mass of gas at constant temperature. 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 541 is distinct because it uses this exact question context and the unit lens rather than a generic particle-model sentence.