Which one of the following processes is endothermic?

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

Answer: (D)

Verified step by step guidance

1. Understand the definition of an endothermic process: it is a process that absorbs heat from the surroundings, meaning heat energy is taken in during the change.
2. Analyze each given process in terms of heat flow: combustion of methane releases heat (exothermic), neutralization of HCl with NaOH releases heat (exothermic), condensation of water vapor releases heat as gas turns to liquid (exothermic).
3. Recognize that melting of ice requires heat input to change solid ice into liquid water, so it absorbs heat from the surroundings, making it an endothermic process.
4. Summarize that processes involving breaking bonds or phase changes from solid to liquid or liquid to gas typically require energy input (endothermic), while processes forming bonds or gas to liquid/solid release energy (exothermic).
5. Conclude that among the options, melting of ice is the endothermic process because it requires heat absorption to overcome the forces holding the solid structure.