If mass M is 12 g and density D is 3 g/mL, what is the volume V in mL?

• A. 2 mL
• B. 6 mL
• C. 12 mL
• D. 4 mL

Answer: (D)

When you relate mass, density, and volume, density tells you how much mass sits in a given volume. Since density = mass/volume, solving for volume gives V = M/D. Plugging in M = 12 g and D = 3 g/mL, you get V = 12 g ÷ 3 g/mL = 4 mL. The grams cancel, leaving the volume in milliliters, which makes sense. The other numbers would come from using different densities (for example, a density of 6 g/mL would give 2 mL, 2 g/mL would give 6 mL, etc.), so 4 mL is the correct result.