Which of the following phase changes is endothermic?

• A. Deposition of water vapor to ice
• B. Condensation of water vapor to liquid
• C. Freezing of liquid water to ice
• D. Melting of ice to liquid water

Answer: (D)

Verified step by step guidance

1. Understand that an endothermic process is one that absorbs heat from the surroundings, meaning energy is required to break intermolecular forces during the phase change.
2. Recall the common phase changes and classify them as either endothermic or exothermic: melting (solid to liquid) and vaporization (liquid to gas) are endothermic, while freezing (liquid to solid) and condensation (gas to liquid) are exothermic.
3. Analyze each given phase change: deposition (gas to solid), condensation (gas to liquid), and freezing (liquid to solid) all release heat, so they are exothermic processes.
4. Recognize that melting (solid to liquid) requires energy input to overcome the forces holding the solid structure, making it an endothermic process.
5. Conclude that among the options, melting of ice to liquid water is the endothermic phase change because it absorbs heat to transition from solid to liquid.