Describe how the particle arrangement and movement differ between a solid and a gas.

In a solid, particles are closely packed in a fixed arrangement and vibrate in place, while in a gas, particles are far apart, move freely, and fill the available space.

Definition lens: Give the precise definition, then add a context sentence that shows how it is used. This question asks: Describe how the particle arrangement and movement differ between a solid and a gas. The correct response is In a solid, particles are closely packed in a fixed arrangement and vibrate in place, while in a gas, particles are far apart, move freely, and fill the available space., because changes of state are explained by particle energy and arrangement. In Changes of state, the marking point should connect directly to distinguish boiling from evaporation using where and how the change occurs. 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 162 is distinct because it uses this exact question context and the definition lens rather than a generic particle-model sentence.