Describe what happens to the particles in a substance when it changes from a solid to a liquid.

When a substance changes from a solid to a liquid, the particles gain energy, which causes them to vibrate more vigorously. This increased energy overcomes some of the forces holding the particles in fixed positions, allowing them to move more freely and flow as a liquid.

Practical lens: Link apparatus, readings, and uncertainty to the exact measurement named in the objective. This question asks: Describe what happens to the particles in a substance when it changes from a solid to a liquid. The correct response is When a substance changes from a solid to a liquid, the particles gain energy, which causes them to vibrate more vigorously. This increased energy overcomes some of the forces holding the particles in fixed positions, allowing them to move more freely and flow as a liquid., because changes of state are explained by particle energy and arrangement. In Changes of state, the marking point should connect directly to state that changes of state are physical changes. 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 Changes of state and the particle model, 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 170 is distinct because it uses this exact question context and the practical lens rather than a generic particle-model sentence.