When sunlight falls on a water surface, what happens to the kinetic energy of water molecules?

Correct answer: It increases, allowing some molecules to become vapour

Correct answer: B. Sunlight transfers energy to the water system. As water molecules gain energy, their average kinetic energy increases, meaning they move more actively. The fastest molecules near the surface may overcome attractive forces holding them in the liquid and escape into the air as water vapour; this process is evaporation. Not every molecule becomes vapour, and evaporation can occur even below the boiling point. A is opposite to the usual effect of absorbed solar energy. C is impossible for moving molecules in ordinary liquid water, and D ignores energy absorption. Temperature represents average kinetic energy, while individual molecules have different energies. Memory cue: more absorbed energy means faster molecules and a greater chance of surface escape.