If a substance has a mass of 9 g and a volume of 3 cm3, what is its density?

• A. 9 g/cm3
• B. 1 g/cm3
• C. 27 g/cm3
• D. 3 g/cm3

Answer: (D)

Density measures how much mass a substance has in a given amount of space. You find it by dividing mass by volume: density = mass / volume.

Here, the mass is 9 g and the volume is 3 cm^3. So the density is 9 g ÷ 3 cm^3 = 3 g/cm^3. The unit g/cm^3 shows mass per unit volume, which is what density represents.

If the density were 9 g/cm^3, the substance would have 9 g in each cubic centimeter, which isn’t the case here. A density of 1 g/cm^3 would mean 1 gram per cubic centimeter, so 3 cm^3 would have 3 g, not 9 g. A density of 27 g/cm^3 would require 27 g in each cubic centimeter, again not matching the given mass and volume.