Question

earthern pots are wrapped with a wet cloth during summers

Answer 1

earthern pot become cool during summer particularly hot day because water evaporation from the pot become easier

Answer 2

Earthen pots are covered with a wet cloth during summer to cool the water .We know that earthen pots have large number of pores in its wall from where water continuously seeps to the outer surface . This water evaporates continuously and takes the heat from the water in  the pot .Thus the remaining water loses its heat and water gets cool.