What does Specific Gravity measure?

Specific gravity is a dimensionless quantity that is defined as the ratio of the weight of a substance to the weight of an equal volume of water at a specified temperature. This measurement provides insight into how heavy or light a substance is in relation to water, which is used as a reference point.

In practical applications, specific gravity can be useful for identifying substances and understanding their behavior, especially in scenarios like firefighting or chemical handling, where knowing whether a material is denser or lighter than water can inform methods of containment and response.

The other choices focus on different properties: the volume of gas produced pertains to gas laws and behaviors, the density of a vapor relates to different calculations in gas dynamics, and the temperature of combustion involves thermodynamics rather than specific gravity. Therefore, the concept of specific gravity is specifically aligned with comparing weights, making the first choice the correct context for this question.