What is specific gravity?

Specific gravity is defined as the weight of a substance compared to an equal volume of water. This measurement is dimensionless and provides a ratio that indicates how dense a substance is relative to water. When a substance has a specific gravity greater than 1, it is denser than water and will sink in it. Conversely, if a substance has a specific gravity less than 1, it is less dense than water and will float. This relationship is crucial in various applications, including water treatment processes, as it helps in understanding how different substances behave when mixed with water.

In contrast, the other choices focus on aspects that do not accurately define specific gravity. For instance, the volume of a particle in relation to water tends to describe concepts like buoyancy rather than specific gravity. The density of solids in water refers to a different form of measurement that does not capture the ratio aspect of specific gravity. Lastly, the amount of water in a given volume of substance can relate more to moisture content or saturation instead of the comparative weight and density characteristics that specific gravity represents.