Which statement correctly describes the arrangement of particles in a solid (Changes of state)

The correct answer is Particles are tightly packed and vibrate in fixed positions..

Boundary lens: Keep this separate from nearby specification points that use similar words but test a different idea. This question asks: Which statement correctly describes the arrangement of particles in a solid (Changes of state). The correct response is Particles are tightly packed and vibrate in fixed positions., because gas pressure comes from particle collisions with container walls. In Changes of state, the marking point should connect directly to use the particle model to explain why gases are less dense than solids or liquids. 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 202 is distinct because it uses this exact question context and the boundary lens rather than a generic particle-model sentence.