What happens to the internal energy of a gas when work is done on it?

The correct answer is It increases.

Application lens: Apply the rule to the specific sample or situation instead of reciting a broad fact. This question asks: What happens to the internal energy of a gas when work is done on it. The correct response is It increases, because gas pressure comes from particle collisions with container walls. In Increasing the pressure of a gas (physics only) (HT only), the marking point should connect directly to (Physics only) (HT only) Apply conservation of energy reasoning to work done on a gas. 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 631 is distinct because it uses this exact question context and the application lens rather than a generic particle-model sentence.