How is "specific gravity" defined in terms of concentration?

Specific gravity is defined as a comparison of a solution's density to that of water. This means that specific gravity is a dimensionless quantity that reflects how heavy a substance is relative to the same volume of water. When you take the density of a substance and divide it by the density of water (which is typically 1 g/cm³ under standard conditions), the result gives you a numerical value that indicates whether the substance will float or sink in water.

This concept is particularly important in fields like chemistry and physics because it helps in understanding the behavior of solutions and how they interact with other substances. For example, a specific gravity greater than 1 indicates a substance that is denser than water, while a value less than 1 indicates a substance that is less dense.

In contrast, the other options provided do not accurately represent the definition of specific gravity. Solute mass, volume ratios, and solubility are important measurements in chemistry but are not related to the specific concept of specific gravity.