What happens to the energy stored within a system when it is heated?

The correct answer is It increases as particle energy rises.

Definition lens: Give the precise definition, then add a context sentence that shows how it is used. This question asks: What happens to the energy stored within a system when it is heated. The correct response is It increases as particle energy rises, because the particle model explains the observable property using particles. In Internal energy, the marking point should connect directly to explain that heating changes the energy stored within a system by increasing particle energy. 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 Internal energy and energy transfers, 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 222 is distinct because it uses this exact question context and the definition lens rather than a generic particle-model sentence.