Which statement about density is true?

The statement that measures the amount of mass per unit volume is true. Density is a fundamental physical property defined as the mass of an object divided by its volume. This relationship helps us understand how tightly matter is packed in a given space and is crucial in many fields, such as engineering, material science, and physics.

When considering density, we typically express it in units like grams per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³). Understanding density is essential for tasks like identifying materials, calculating buoyancy, and performing fluid dynamics analyses.

The context of the other statements clarifies why they are not accurate. Density does not define the volume of a solid object, as it is derived from both mass and volume rather than measuring volume directly. Although density may remain relatively constant for a particular substance under specific conditions, it can change with temperature and pressure, thus it is not an unchanging value. Lastly, density is inherently related to mass; it cannot exist without mass, making the assertion that it has no relation to mass incorrect.