Question

how does the rate of the diffusion changes changes with tonn

what is differant between evaporation and biolinng

why does the evaporation take place only from the surface of liquid.

Answer 1

Evaporation	Boiling
It occurs at the surface of the liquid.	It occurs at in the entire mass of the liquid, i.e. in the bulk of the phase.
It is a slow process	It is a rapid process.
It occurs at all temperatures	It occurs at specific temperature, known as the boiling temperature of the liquid.
The motion of few particles is fast and while of others is slow.	The motion of all the particles is fast.

During evaporation the molecules in the liquid state escape into vapour phase, which requires total cut off the molecule from the attractive forces of other molecules in the liquid phase. This is possible only for the molecules present at the surface thus evaporation occurs only at the surface of the liquid.