It knows that when water evaporates, it carries heat energy away with it.
So your body puts some water out on your skin, and hopes that it will
evaporate. We call that "perspiring" or "sweating".
Number of moles = number of atoms/Avogadro's number
= (4.8x10^25)/(6.02x10^23)
=79.7 mol (3sf)