Use the particle model to explain why solids have fixed shapes and liquids and gases flow.

Use the particle model to explain why solids have fixed shapes and liquids and gases flow. Exam lens: Write the relationship, substitute values only when needed, and finish by interpreting the result. In Changes of state, this means gas pressure comes from particle collisions with container walls. The answer should use the approved wording from Changes of state and the particle model, include solid, liquid, gas, particle model, and avoid drifting into another section of Particle model of matter. For revision, practise saying the exact objective aloud, then add the one calculation, particle movement, collision, graph, or practical detail that makes the statement true. A strong exam response for checkpoint 28 is specific to use the particle model to explain why solids have fixed shapes and liquids and gases flow and does not reuse a generic explanation from a neighbouring objective.