Q1: Heat dissipation in cooling towers is mainly by

ANS:C - evaporation

Evaporation is a process by which a liquid substance changes into a gaseous state when its molecules gain enough energy to overcome the attractive forces holding them together in the liquid phase. This typically occurs at the surface of the liquid. During evaporation, molecules near the surface of the liquid gain sufficient kinetic energy from the surrounding environment (usually heat) to break free from the liquid phase and enter the gas phase. As these molecules escape, they carry away energy, resulting in a cooling effect on the remaining liquid. This is why sweating helps cool the body—it's the result of evaporation of sweat from the skin surface. Several factors influence the rate of evaporation, including temperature, humidity, surface area, and the presence of air movement. Higher temperatures and lower humidity levels generally promote faster evaporation. Additionally, increasing the surface area of the liquid exposed to the surrounding air and enhancing air movement over the liquid surface can also accelerate the evaporation process. Evaporation plays a crucial role in various natural and industrial processes, including the water cycle, drying of wet surfaces, cooling systems such as cooling towers, and the production of salt from seawater, among others.