Question

On heating the solids, the intermolecular distance between molecules:
A.Increases
B.Decreases
C.Remain same
D.Depends on particles

Answer 1

Hint:
From kinetic theory of gases it's clear that kinetic energy of a molecule is a function of temperature of a substance. Hence if we heat solids, it leads to the higher kinetic energy of particles and thus less intermolecular force of attraction between molecules.

Complete step by step answer:
In the case of solids, the intermolecular forces between particles are very large and as a result the intermolecular spaces are very small. As a result, the molecules in a solid can vibrate about their mean positions, but cannot change their positions. Due to this molecular arrangement, solids have definite shape and definite volume.
The phase of a substance depends on the balance between the intermolecular forces and the kinetic energy of the individual molecules or particles. The kinetic energy of a molecule is a function of the temperature of the substance and keeps the molecules apart and moving around. Hence, the increase in kinetic energy of individual molecules is because of the increase in temperature of solid.
As we mentioned, in a solid, the atoms or molecules are closely packed together and have fixed position. On heating, their kinetic energy pushes neighbouring atoms or molecules apart from each other. This pushing of atoms or molecules results in a slightly increased distance between molecules, and volume of solid also increases.
Hence on heating solids, intermolecular forces are becoming weak and intermolecular distance increases.
So, the correct answer is “Option A”.

Note:
The change in the size of a body in terms of length, area or volume, as a result of change in temperature can also be described as thermal expansion of solids. Thermal expansion is not negligible but relatively small for liquids and solids and is large in case gases. The change in temperature can be associated with phase transitions such as melting, boiling, and subliming.