Why are gases less dense than solids or liquids according to the particle model (Changes of state)

The correct answer is Particles in gases are further apart and move freely..

Evidence lens: Use the data, graph feature, practical observation, or particle behaviour that proves the answer. This question asks: Why are gases less dense than solids or liquids according to the particle model (Changes of state). The correct response is Particles in gases are further apart and move freely., 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 201 is distinct because it uses this exact question context and the evidence lens rather than a generic particle-model sentence.