Describe how the particle model can explain the flow of liquids and gases.

In liquids, particles are close together but can move past one another, allowing the liquid to flow and take the shape of its container. In gases, particles are much further apart and move rapidly in all directions, which enables them to expand and fill the available space, also allowing them to flow.

Boundary lens: Keep this separate from nearby specification points that use similar words but test a different idea. This question asks: Describe how the particle model can explain the flow of liquids and gases. The correct response is In liquids, particles are close together but can move past one another, allowing the liquid to flow and take the shape of its container. In gases, particles are much further apart and move rapidly in all directions, which enables them to expand and fill the available space, also allowing them to flow., 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 solids have fixed shapes and liquids and gases flow. 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 190 is distinct because it uses this exact question context and the boundary lens rather than a generic particle-model sentence.