Complete the definition:Density is …… the size of the object.… the mass per unit volume for a substance.… the weight of a substance.… the mass and volume of a substance.

Density is the mass per unit volume for a substance. This means that it measures how much mass is contained in a given volume of a substance. It is usually expressed in units such as grams per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³).

The size of the object does not define density, as a larger object may be less dense if it is made of a lighter material.

Density is not the weight of a substance, because weight is a measure of the force exerted by gravity on an object, while density is a measure of mass per unit volume.

Finally, while density does involve both the mass and volume of a substance, it is not simply the mass and volume of a substance. It is the ratio of the mass to the volume.