Relative Density

Density of a substance is defined as the ratio of its mass per unit volume. Its unit is kg/m3 in S.I. system.
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Density =

Relative density of a substance is defined as the ratio of the density of substance to the density of water.

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Relative density of the substance =
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It is a mere number and it has no units.

Relative density is also known as specific gravity. The relative density of a substance is "the ratio of the mass of a given volume of the substance, to the mass of an equal volume of water." The density of pure water is 1000 kg/m3 and the density of sea water is 1030 kg/m3. The density of gold is 19300 kg/m3.

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