Question

Define density ?
How is it related to Relative density ?

give si units of both IF ANY ...

Answer 1

density is the mass per unit volume.
density of a substance is related to relative density as relative density is density of a substance to that of water.
the SI unit of density is kg/m^3
the relative density has no unit.
hope it helps!!!!!

Answer 2

Density:
It is given by mass by volume.
It's SI unit is kg/m^3
Relative density:
Relative density is given by the density of a substance by density of water at 4 degree Celsius. 
It is defined as the ratio of a substance 's density to water's density at 4 degree Celsius. It is also known as specific gravity. 
Since it's a ratio there's no specific units for it. 
Thanks