Which of the following processes is exothermic?

• A. Evaporation of water
• B. Photosynthesis in plants
• C. Combustion of methane
• D. Melting of ice

Answer: (C)

Verified step by step guidance

1. Understand the definition of an exothermic process: it is a process that releases heat to the surroundings, meaning the system loses energy.
2. Analyze each given process to determine if it releases or absorbs heat:
3. 1. Evaporation of water: this is a phase change from liquid to gas, which requires energy input to overcome intermolecular forces, so it is endothermic (absorbs heat).
4. 2. Photosynthesis in plants: this process converts carbon dioxide and water into glucose and oxygen using sunlight energy, so it requires energy input and is endothermic.
5. 3. Combustion of methane: this is a chemical reaction where methane reacts with oxygen to produce carbon dioxide and water, releasing energy in the form of heat and light, so it is exothermic.