CBSE Class 9 Answered

(a) The water vapour present in the air, on coming in contact with the cold glass of water, loses energy and gets converted to a liquid state (gets condensed), which can be seen as tiny water droplets.

(b) In summer we perspire more. Cotton being a good absorber of water helps in absorbing the sweat and exposes it to the atmosphere for evaporation. When sweat evaporates from our body, it takes away the heat from our body. Thus, our body loses heat and gets cooled.

(c) The sprinkled water evaporates by taking large latent heat of vapourisation from the roof or open ground and surrounding air causing cooling of the place.