A substance has a density of 2.5 g/cm³ and occupies a volume of 80 cm³. What is its mass (Density of materials) (Density of materials; definition focus: Rearrange the density equation to solve for mass, volume or density) (Density of materials; definition focus: Rearrange the density equation to solve for mass, volume or density)

The correct answer is 200 g.

Unit lens: Check the units before giving the final statement so the physics quantity is not swapped. This question asks: A substance has a density of 2.5 g/cm³ and occupies a volume of 80 cm³. What is its mass (Density of materials) (Density of materials; definition focus: Rearrange the density equation to solve for mass, volume or density) (Density of materials; definition focus: Rearrange the density equation to solve for mass, volume or density). The correct response is 200 g, 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 rearrange the density equation to solve for mass, volume or density. 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 49 is distinct because it uses this exact question context and the unit lens rather than a generic particle-model sentence.