Question

(a) What is the difference between the density and relative density of a substance?a
(b) If the relative density of a substance is 7.1, what will be its density in SI units?

Answer 1

a)

Density	Relative density
The density of a material is its mass per unit volume.	Relative density of a substance is the ratio of density of a substance to the density of water.
$\rho =\frac{m}{V}$	$RD=\frac{{\rho }_{\mathrm{substance}}}{{\rho }_{\mathrm{water}}}$
SI unit of density is kg/m3.	Relative density is a dimensionless quantity.

b) The density of the substance in SI unit would be 7.1 kg/m³.