The ratio of the mass of a given volume of liquid compared with the mass of an equal volume of water at the same temperature is called:

The ratio of the mass of a given volume of liquid compared with the mass of an equal volume of water at the same temperature is called:

• A. Vapor density.
• B. Flash point.
• C. Surface to mass ratio.
• D. Specific gravity.

Answer: (D)

This question tests how we compare how heavy a liquid is for the same amount of space relative to water. Since density is mass per volume, the ratio of masses for the same volume of liquid and water equals the ratio of their densities. Water acts as the reference standard with density of about 1, so this ratio is the liquid’s specific gravity. It’s a dimensionless number that tells you how dense the liquid is compared with water. Vapor density would apply to gases relative to air, not liquids; flash point relates to ignition temperature; and surface to mass ratio isn’t a standard property.

This question tests how we compare how heavy a liquid is for the same amount of space relative to water. Since density is mass per volume, the ratio of masses for the same volume of liquid and water equals the ratio of their densities. Water acts as the reference standard with density of about 1, so this ratio is the liquid’s specific gravity. It’s a dimensionless number that tells you how dense the liquid is compared with water.

Vapor density would apply to gases relative to air, not liquids; flash point relates to ignition temperature; and surface to mass ratio isn’t a standard property.