Specific Gravity is described as the ratio of the density of a substance to the density of water for liquids and solids, and to air for gases. Which option correctly reflects this definition?

Specific Gravity is described as the ratio of the density of a substance to the density of water for liquids and solids, and to air for gases. Which option correctly reflects this definition?

• A. The ratio of density to air for all substances
• B. The ratio of density to water for liquids and solids, and to air for gases
• C. The ratio of density to water for all substances
• D. The ratio to standard density chosen at random

Answer: (B)

Specific gravity is a dimensionless ratio that compares the density of a substance to a reference density. For liquids and solids, that reference is water, so SG = density of the substance divided by density of water. For gases, the reference is air, so SG = density of the substance divided by density of air. The option that states this exact relationship is the correct reflection of how specific gravity is defined. Other choices misstate what the reference density should be—using air for all substances or water for all substances—or suggest a random standard, which doesn’t align with the standard definition.

Specific gravity is a dimensionless ratio that compares the density of a substance to a reference density. For liquids and solids, that reference is water, so SG = density of the substance divided by density of water. For gases, the reference is air, so SG = density of the substance divided by density of air. The option that states this exact relationship is the correct reflection of how specific gravity is defined. Other choices misstate what the reference density should be—using air for all substances or water for all substances—or suggest a random standard, which doesn’t align with the standard definition.