Give reasons: (i) Evaporation causes cooling. (ii) Falling liquids drops are spherical. (iii) Vapour pressure of acetone is less than that of ether at same temperature.
(i) This is due to the reason that the molecules which undergo evaporation are high en molecules and therefore, the kinetic energy of the remaining molecules becomes less. Since the remaining molecules have lower average kinetic energy, their temperature becomes low. (ii) This is due to surface tension of liquids. Due to surface tension, the to make surface area to be minimum and for a given volume, sphere has the minimum surface area. Therefore the falling liquid drops are spherical. (iii) Intermolecular forces are stronger in acetone than in ether. Thus the vapour press acetone is less than ether.
