Which formula expresses mass in terms of density and volume?

• A. M = D x V
• B. D = M x V
• C. V = M ÷ D
• D. M ÷ V = D

Answer: (A)

Mass is what you get when you multiply how dense something is by how much space it occupies. Density is defined as density = mass/volume, so rearranging that relation to solve for mass gives mass = density × volume. In symbols, M = D × V. This form directly expresses mass in terms of density and volume, which is exactly what the question asks.

The other options don’t express mass in terms of density and volume. One option would place density as mass times volume, which would clash with the units of density. Another option rearranges to express volume in terms of mass and density, which is a valid rearrangement but not what the question asks. The remaining form expresses density, not mass, though it’s just another way to view the same relationship.