Which of the following chemical or physical changes is an endothermic process?

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

Answer: (A)

Verified step by step guidance

1. Understand the difference between endothermic and exothermic processes: Endothermic processes absorb heat from the surroundings, while exothermic processes release heat.
2. Analyze each option to determine whether heat is absorbed or released during the change:
3. 1. Melting of ice: This is a phase change from solid to liquid, which requires heat input to break the hydrogen bonds in ice, so it absorbs heat (endothermic).
4. 2. Condensation of water vapor: This is a phase change from gas to liquid, which releases heat to the surroundings (exothermic).
5. 3. Neutralization of hydrochloric acid with sodium hydroxide: This is a chemical reaction that typically releases heat (exothermic).
6. 4. Combustion of methane: This is a chemical reaction that releases a large amount of heat (exothermic).
7. Conclude that the melting of ice is the endothermic process because it requires heat absorption to change phase from solid to liquid.