In which of the following case evaporation of water will be slowest? (a) A tray of water kept in sunlight. (b) A kettle of water kept on a burner. (c) A glass of water kept in a room. (d) A bucket of water kept on rooftop.

(c): A glass of water kept in a room.

Evaporation is directly proportional to temperature when temperature increases, evaporation also increases. Temperature in the room will be lower as compared to the temperatures of sunlight, burner and rooftop. So, a glass of water kept in a room has slowest water evaporation.