In which one of the following processes is the system endothermic?

• A. Neutralization of hydrochloric acid with sodium hydroxide
• B. Condensation of water vapor
• C. Melting of ice to liquid water
• D. Combustion of methane

Answer: (C)

Verified step by step guidance

1. Understand the definition of an endothermic process: it is a process in which the system absorbs heat from the surroundings, resulting in a positive heat flow into the system.
2. Analyze each given process to determine whether heat is absorbed or released:
3. 1. Neutralization of hydrochloric acid with sodium hydroxide is an exothermic reaction because it releases heat when an acid and base react to form water and salt.
4. 2. Condensation of water vapor is an exothermic process because when vapor condenses to liquid, it releases heat to the surroundings.
5. 3. Melting of ice to liquid water is an endothermic process because heat is absorbed by the ice to overcome the forces holding the solid structure, causing it to melt.
6. 4. Combustion of methane is an exothermic reaction because it releases a large amount of heat as methane reacts with oxygen to form carbon dioxide and water.