Q 2. How does the water kept in an earthen pot (matka) become cool during summer?
The water inside the earthen pot become cold during the summer because the earthen pot is porous with a lot of pores in it. So, water comes out on the surface of the earthen pot, and this water gets evaporated.
And thus the temperature of water present inside the pot has a much lower temperature than outside, and hence water becomes cold.