Question

Boiling is a bulk phenomenon which occur only at boiling point while evaporation is a surface phenomenon which occur at any tempraturein boiling no physical state is changed in e

Answer 1

Boiling point is a point of temperature of liquid at which the liquid exert a pressure equal to atmospheric pressure in its container.In boiling the heat is supplied at the bottom of the liquid .so the liquid molecules at bottom get heat and their volume is increased and density is decreased.So lower density molecules come to surface and denser molecules at the surface go to bottom .By this process all molecules get heated and thus aquire more kinetic energy.due to this molecules collide each other ,high pressure is produced .When this pressure is equal to atmospheric pressure ,the liquid is said to boil. Boiling point is sharp.Here physical state is not changed . Evaporation is the process in which liquid molecules are changed to gasious molecules due to temperature.it is not sharp occurs in normal temperature and above it.