Which of the following statements about density is true?

The correct answer is Density changes with temperature and pressure..

Method lens: First identify the measured quantity, then match the equation or particle idea to the command word. This question asks: Which of the following statements about density is true. The correct response is Density changes with temperature and pressure., 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 identify density in kilograms per metre cubed or grams per centimetre cubed, mass in kilograms or grams and volume in metres cubed or centimetres cubed. 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 20 is distinct because it uses this exact question context and the method lens rather than a generic particle-model sentence.