Which statement correctly defines density?

Which statement correctly defines density?

• A. Density measures temperature.
• B. Density is mass per unit volume.
• C. Density is equal to volume.
• D. Density is the force per area.

Answer: (B)

Density describes how much mass is packed into a given volume. It is defined as density = mass divided by volume, so it tells you how compact the material is. If the same mass takes up more space, the density is lower; if more mass fits into the same space, the density is higher. Common units include kg/m^3 in SI, and for many liquids and solids g/cm^3 or g/mL are convenient. For example, a cubic centimeter of lead weighs much more than a cubic centimeter of water, so lead has a higher density. Temperature and phase can influence density because they change volume, especially for gases, where density changes noticeably with temperature and pressure. Density is not a measure of temperature, it is not equal to volume, and it is not a measure of force per area (that quantity is pressure).

Density describes how much mass is packed into a given volume. It is defined as density = mass divided by volume, so it tells you how compact the material is. If the same mass takes up more space, the density is lower; if more mass fits into the same space, the density is higher. Common units include kg/m^3 in SI, and for many liquids and solids g/cm^3 or g/mL are convenient. For example, a cubic centimeter of lead weighs much more than a cubic centimeter of water, so lead has a higher density. Temperature and phase can influence density because they change volume, especially for gases, where density changes noticeably with temperature and pressure. Density is not a measure of temperature, it is not equal to volume, and it is not a measure of force per area (that quantity is pressure).