Question

What is meant by density of a substance?

Answer 1

Hint: We know that density is a physical property of matter. Density expresses the relationship between the mass and the volume of matter. If two substances have equal volumes, then the substance with more mass is more dense.

Complete step by step solution:
Density is defined as the ratio of mass of the object to the volume of the object. Different substances have different densities.
The mathematical expression for density is as follows:
${\text{Density}} = \dfrac{{{\text{Mass}}}}{{{\text{Volume}}}}$
The mass of a substance is expressed in kilograms and the volume is expressed in litre. Thus, the unit of density is ${\text{kg }}{{\text{L}}^{ - 1}}$.
The property of a system which is independent of the amount of matter present in the system is known as an intensive property. The density of a substance does not depend on the amount of the matter. The density of one kilogram and two kilogram of water is the same. Thus, density is an intensive property.
If we drop a block of wood and a metal nail having the same mass in water the wooden block floats and the metal nail sinks in water. This is because the density of the metal nail is more than that of the block of wood. From this we can conclude that for the same mass of two objects, higher the volume of an object, lesser is its density.

Note:
The density of substance varies with temperature and pressure. When we apply pressure to an object, its volume decreases and thus, density increases. When we increase the temperature of an object, its volume increases and thus, density decreases.