Specific gravity is defined as the ratio of the density of a substance to the density of what standard?

Specific gravity is defined as the ratio of the density of a substance to the density of what standard?

• A. Water
• B. Air
• C. Oil
• D. Mercury

Answer: (A)

Specific gravity is a unitless ratio that compares how dense a material is to a standard reference density. That reference is the density of water, usually defined at 4°C, which sets the baseline at 1.000 g/cm³. By dividing the material’s density by water’s density, you get a number that shows how many times denser the material is than water (or less dense if the value is below 1). The other options aren’t the standard reference because water is the agreed baseline for most SG calculations; air is used as a reference in some gas contexts, and the densities of oil or mercury are properties of those substances, not the reference standard.

Specific gravity is a unitless ratio that compares how dense a material is to a standard reference density. That reference is the density of water, usually defined at 4°C, which sets the baseline at 1.000 g/cm³. By dividing the material’s density by water’s density, you get a number that shows how many times denser the material is than water (or less dense if the value is below 1). The other options aren’t the standard reference because water is the agreed baseline for most SG calculations; air is used as a reference in some gas contexts, and the densities of oil or mercury are properties of those substances, not the reference standard.