Question

Which of the following is true about the density of a substance?

• A. It is a derived quantity.
• B. The unit of density in SI system is kilogram per metre${}^3$.
• C. The density of a substance can be measured if the mass of the substance for a certain volume is known.
• D. Density is a vector quantity

Answer 1

Answer: (A), (B), (C)

The correct options are
A It is a derived quantity.
B The unit of density in SI system is kilogram per metre${}^3$.
C The density of a substance can be measured if the mass of the substance for a certain volume is known.

Let the mass of the substance be $m$ and its volume be $V$. Then the density of the substance is defined as the ratio of mass to the volume of the body.

Thus the density of a substance can be derived as $\rho =\frac{m}{V}$

SI unit of mass is $kg$ and that of the volume is $m^3$. Thus SI unit of density is $kg/m^3$.

The density of a substance is a scalar quantity, not a vector quantity as it has magnitude only.

Hence options A, B and C are correct.