Vaporisation occurs when _______.

Vaporisation occurs when _______.

a. Vapour pressure > pressure above liquid surface at a temperature
b. Vapour pressure < pressure above liquid surface at a temperature
c. Vapour pressure = pressure above liquid surface at a temperature
d. None of the above

Correct Answer : a. Vapour pressure > pressure above liquid surface at a temperature.

Explanation :

Vapour pressure is the pressure exerted by the vapour formed at the free surface of a liquid. This phenomenon occurs when surface molecules escape from the surface of liquid by overcoming the molecular attractive forces. This phenomenon of escaping the surface molecules from the liquid surface is called vaporisation and this is possible only when vapour pressure is greater than the pressure above the liquid surface.