The correct relation between density and relative density is :

1. R.D. = $\dfrac{\text{Density of substance in g cm}^{-3}}{1.0{\text{ g cm}^{-3}}}$

2. R.D. = $\dfrac{\text{Density of substance in g m}^{-3}}{1.0{\text{ g/cm}^{3}}}$

3. R.D. = $\dfrac{\text{Density of substance in kg cm}^{-3}}{1.0{\text{ g cm}^{3}}}$

4. None of these

R.D. = $\dfrac{\text{Density of substance in g cm}^{-3}}{1.0{\text{ g cm}^{-3}}}$

Reason — In C.G.S. system, density of water at 4°C is 1 g cm^-3, so the relative density of a substance is equal to the numerical value of density of that substance.

Thus, R.D. = $\dfrac{\text{Density of substance in g cm}^{-3}}{1.0{\text{ g cm}^{-3}}}$