Question

The ratio of density of the substance to density of water of ${4^ \circ }C$ is known as ____.

Answer 1

Hint: Density is an object's mass divided by its volume. Density also has units of gram per cubic inch. The ratio of the density (the mass of the unit volume) of a substance to the density of the reference material is the relative density, or specific gravity.

Complete step by step answer:

The ratio of the density (the mass of the unit volume) of a substance to the density of the reference material is the relative density, or specific gravity. For liquids, the specific gravity is almost always determined with respect to the densest water (at ${4^ \circ }C$ or ${39.2^ \circ }F$ ); for gases, air at room temperature ( ${20^ \circ }C$ or ${68^ \circ }F$ ) is the reference. In scientific use, the word "relative density" is also preferred.

If the relative density of the material is less than one, it is less dense than the reference; if it is greater than $1$, it is denser than the reference. The densities are equal if the relative density is exactly $1$; that is, the same quantities of the two substances have the same mass. If water is the reference material, then a substance of less than $1$ relative density (or specific gravity) can float in water. An ice cube, for instance, can float with a relative density of around $0.91$ . 

A material with a relative density greater than $1$ is going to sink.

Hence, from the above discussions we can conclude that the ratio of density of the Substance to density of water of ${4^ \circ }C$ is known as specific gravity.

Note: Here we have to pay attention to the temperature and also whether density of water or gas is mentioned. If options between relative density and specific gravity are given, then the answer would be both as both are the same.