What method can be used to determine the volume of an irregular solid?

The correct answer is Displacement of water.

Definition lens: Give the precise definition, then add a context sentence that shows how it is used. This question asks: What method can be used to determine the volume of an irregular solid. The correct response is Displacement of water, because density links mass and volume, so the answer must preserve which quantity is being calculated. In Density of materials, the marking point should connect directly to describe how to determine the volume of an irregular solid using displacement of water. 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 78 is distinct because it uses this exact question context and the definition lens rather than a generic particle-model sentence.