(a) Define density. What is the SI unit of density ?
(b) Define relative density. What is the SI unit of relative density ?
(c) The density of turpentine is $840\ kg/m^3$. What will be its relative density ? $(Density\ of\ water=1000\ kg/m^3)$

(a). Density: The mass of a substance per unit volume is known as the density of the substance.

$\boxed{density=\frac{mass}{volume}}$

The SI unit of density is $kg/m^3$.

(b). Relative density: The ratio of the density of a substance to the density of water is known as the relative density of the substance.

$\boxed{relative\ density=\frac{density\ of\ the\ substance}{density\ of\  water}}$

(c).  The density of turpentine $=840\ kg/m^3$

Density of the water $=1000\ kg/m^3$

Therefore, relative density of turpentine $=\frac{840}{1000}$

$=0.84$