Question

Give reasons for the following :
(a) A liquid generally flows easily.
(b) Ice at `0^(@)C` appears colder in the mouth than water at `0^(@)C`.
(c ) Doctors advise to put strips of wet cloth on the forehead of a person having high fever.

Answer 1

(a) The intermolecular forces in a liquid are weak. Its molecules are able to slide over one another and liquid generally flows easily.
(b) Latent heat of fusion of ice is quite high. In the mouth, ice absorbs this heat and melts. That is why ice at `0^(@)C` gives more cooling sensation in the mouth than water at the same temperature.
(c ) As water evaporates from the strips of wet cloth placed on the forehead of a person, it absorbs heat from the body. The body temperature gets lowered and the person get some relief from fever.