Density of any other substance with respect to the density of water at 4°C is called relative density. Mathematically,
\(R.D. = \frac{Density\,of\,the\,substance}{Density\,of \,water\,at\, 4°C}\)
We know that Density = \(\frac{Mass}{Volume}\)
∴ Relative density = \(\frac{Mass\,of\, the substane/ Volume\, of \, substance}{Mass\,of\,water/Volume\,of\,water}\)
Since the volume of substance is equal to volume of water,
Relative density = \(\frac{Mass\,of\,certain\,volume\,of\,substance}{Mass\,of\,equal\,volume\,of\,water}\)
Thus, the ratio of mass of a given volume of a substance to the mass of an equal volume of water at 4°C also denotes relative density.
