Which of the following processes is endothermic?

• A. Condensation of water vapor
• B. Neutralization of hydrochloric acid with sodium hydroxide
• C. Combustion of methane
• 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: condensation of water vapor releases heat (exothermic), neutralization reactions typically release heat (exothermic), and combustion reactions release a large amount of heat (exothermic).
3. Recognize that melting of ice requires heat to break the hydrogen bonds holding the solid structure, so heat is absorbed from the surroundings, making it an endothermic process.
4. Recall that phase changes from solid to liquid (melting) always require energy input to overcome intermolecular forces, which is characteristic of endothermic processes.
5. Conclude that among the options, melting of ice is the process that absorbs heat and is therefore endothermic.