146.

On the basis of kinetic molecular theory of liquids, how can you explain the following properties of liquids:
(i) Volume                             (ii) Density
(iii) Compressibility                (iv) Diffusion?

1. Volume. Liquids have a definite volume. This is because the intermolecular forces of attraction in a liquid are quite strong. As a result, the molecules are not completely free to occupy all the space available (as gases do).

2. Density. Liquids have much higher density than gases. This is because the molecules in the liquid state are closely packed. Hence, the volume for the same amount of the substance in the liquid state is less as compared to the volume in the gaseous state. Consequently, the density (m v) is greater in a liquid state.

3. Compressibility. Liquids are much less compressible than gases. This is due to the fact that in comparison to gases, there is very little empty space between the molecules in the case of liquids.

4. Diffusion. Liquids diffuse slowly in comparison to gases. This is because the molecules in the liquid state are quite close to each other. Therefore, a molecule of the liquid has to undergo a number of collisions in the neighbouring molecules. As a result of innumerable collisions, there is a more obstruction for the movement of the molecules of a liquid. Thus diffusion takes place slowly.