State whether true or false.
The density of a substance is defined as the mass per unit volume of that substance.
(A) True
(B) False

Hint: The density can be defined by dividing the mass of a substance to the volume of substance. Where the unit of mass is kg and the unit of volume is cubic meter. It is generally represented by the symbol $\rho $. That is, density is mass divided by volume. The density of a material generally depends on its mass and volume.

Formula used:
The density of a substance is given by,
$\rho =\dfrac{m}{V}$
where,
$m$ is the mass of the substance
$V$ is the volume of substance

Complete solution:
The density of a substance is given by,
$\rho =\dfrac{m}{V}$
where,
$m$ is the mass of the substance
$V$ is the volume of substance

The value of densities of different materials vary from one to another. It can depend on the temperature and pressure of the materials also. That is, because the pressure is related to the volume. While the temperature of a substance decreases density also increases. The specific volume is the reciprocal of its density. It is an intensive property.

The density of a substance is always defined as the mass per unit volume of that substance. Thus the given statement is true.

Hence, option (A) is correct.

Note: The density is an example of intensive property. Intensive means as the amount of matter changes, the property of matter doesn’t change. That is, it is independent of size. The density of a material generally depends on its mass and volume. Since volume is also related to pressure, the density depends on pressure also.