What is meant by a physical change in the context of changes of state?

A physical change refers to a change in the state of a substance without altering its chemical composition. For example, when ice melts to form water, it changes from solid to liquid, but the chemical structure of water remains the same.

Unit lens: Check the units before giving the final statement so the physics quantity is not swapped. This question asks: What is meant by a physical change in the context of changes of state. The correct response is A physical change refers to a change in the state of a substance without altering its chemical composition. For example, when ice melts to form water, it changes from solid to liquid, but the chemical structure of water remains the same., 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 169 is distinct because it uses this exact question context and the unit lens rather than a generic particle-model sentence.