Which expression correctly defines the density of a substance in terms of mass and volume?

Which expression correctly defines the density of a substance in terms of mass and volume?

• A. D = V / m
• B. D = m × V
• C. D = m^2 / V
• D. D = m / V

Answer: (D)

Density tells you how much mass sits in a given volume. If you keep the mass the same but pack it into a smaller space, the density goes up; if you give it more space, the density goes down. That’s why density is defined as mass divided by volume. It has the right relation and units, such as kg per cubic meter or g per cubic centimeter. For example, 2 kilograms in 1 liter gives a density of 2 kg/L. Other forms don’t match what density measures. Volume divided by mass would be the inverse relationship, not density. Multiplying mass by volume yields a quantity with different units, not density. Mass squared divided by volume also has the wrong units.

Density tells you how much mass sits in a given volume. If you keep the mass the same but pack it into a smaller space, the density goes up; if you give it more space, the density goes down. That’s why density is defined as mass divided by volume. It has the right relation and units, such as kg per cubic meter or g per cubic centimeter. For example, 2 kilograms in 1 liter gives a density of 2 kg/L.

Other forms don’t match what density measures. Volume divided by mass would be the inverse relationship, not density. Multiplying mass by volume yields a quantity with different units, not density. Mass squared divided by volume also has the wrong units.