What is the formula for calculating density?

The correct answer is Density = mass / volume.

Unit lens: Check the units before giving the final statement so the physics quantity is not swapped. This question asks: What is the formula for calculating density. The correct response is Density = mass / volume, 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 density of a liquid using a balance and measuring cylinder. 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 85 is distinct because it uses this exact question context and the unit lens rather than a generic particle-model sentence.