What term describes the ratio of the weight of a substance to the weight of an equal volume of water?

The term that accurately describes the ratio of the weight of a substance to the weight of an equal volume of water is specific gravity. Specific gravity is a dimensionless quantity that compares the density of a substance to the density of water at a standard temperature (typically 4°C, where water is at its maximum density).

When determining specific gravity, if the specific gravity of a substance is greater than 1, it means that the substance is denser than water, while a value less than 1 indicates that it is less dense than water. This property is crucial in various fields including materials science, geology, and engineering, as it helps in understanding how substances will behave when placed in water, which is often a common scenario in construction and environmental assessments.

When considering the other options, density refers to the mass per unit volume of a substance and is usually expressed in specific units like grams per cubic centimeter (g/cm³). Viscosity measures a fluid’s resistance to flow, while water content relates to the amount of water contained within a substance. Each of these terms refers to different properties and must not be confused with specific gravity, which is fundamentally a comparative measure rather than an intrinsic property.