What effect does compressing a gas have on its internal energy?

The correct answer is It increases the internal energy.

Particle lens: Describe arrangement, motion, spacing, collisions, or energy changes only when they are relevant here. This question asks: What effect does compressing a gas have on its internal energy. The correct response is It increases the internal energy, because gas pressure comes from particle collisions with container walls. In Particle motion in gases, the marking point should connect directly to use the particle model to explain why gas pressure changes when gas particles collide 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 504 is distinct because it uses this exact question context and the particle lens rather than a generic particle-model sentence.