The gases have two principal specific heats but solids and liquied have only one specific heat. Why ?

Explanation

When heat is supplied to a gas, there is increases in its volume and pressure. So energy is requird for the expansion of gas. We have two principal spacific heats of a gas, one at constant pressure and another at constant volume. When heat is supplied to a solid or liquid there in negligible expansion of the solid or liquied. That is why there is only one value of specific heat fo solid or liquid which is at constatn volume and pressure. so energy is required for the expansion of gas. we have two principle specific heats of a gas. we have two principle specific heats of a gas, one at constant pressure and another at constant volume.
When heat is supplied to a solid or liquid, there is negligble expansion of the solid or liquid. That is why there is only one value of specific heat of solid or liquid which is at constant volume.