Question

How does evaporation before for the boiling

Answer 1

Evaporation starts before boiling too, because some of the molecules of top layer of the liquid absorb much energy to get vapourise and gets vaporised.

Answer 2

Hey bro... Boiling starts at 100°C.. before that, evaporation takes place.. because of low heat... when temperature rises up.. evaporation level increases... & when temperature goes up to 100°C.. it starts boiling :-)