What does density of a material describe?

• A. The weight of it
• B. The color
• C. The volume
• D. The mass per area

Answer: (A)

Density is the amount of mass packed into a given volume. It tells how tightly matter is held together in a material. If you compare two samples with the same volume, the one with more mass has higher density; similarly, for a fixed mass, a smaller volume means higher density. This quantity is an intrinsic property that helps identify substances and compare them, and for gases density changes with temperature and pressure. Weight, on the other hand, is the gravitational force on a mass, so it’s related but not the density itself. Volume is the space the material occupies and is used to compute density, not density itself. Mass per area describes mass per unit area—surface density—which is different from the standard density. So density fundamentally describes mass per unit volume, expressed in units like kg per cubic meter.