Density is defined as which of the following?

• A. Mass per unit volume
• B. Mass
• C. Volume
• D. Weight

Answer: (A)

Density tells you how much matter is packed into a given amount of space. It is defined as mass per unit volume, usually written as density = mass ÷ volume. This means that for the same volume, a substance with a larger mass is denser, and for the same mass, a smaller volume is denser. The other ideas—mass alone or volume alone—do not describe how tightly matter is packed, and weight is the gravitational force on a mass, not density. For example, a cubic centimeter of lead has much more mass than a cubic centimeter of styrofoam, so lead is denser. Common density units include g/cm^3 or kg/m^3.