Which of the following changes of state involves atoms or molecules gaining energy?

• A. Sublimation (solid to gas)
• B. Melting (solid to liquid)
• C. Freezing (liquid to solid)
• D. Condensation (gas to liquid)

Answer: (B)

Verified step by step guidance

1. Understand that changes of state (phase changes) involve either absorption or release of energy by atoms or molecules.
2. Recall that when a substance changes from a solid to a liquid (melting) or from a solid directly to a gas (sublimation), the particles gain energy to overcome intermolecular forces.
3. Recognize that during melting and sublimation, energy is absorbed, so atoms or molecules gain kinetic energy.
4. Note that freezing (liquid to solid) and condensation (gas to liquid) involve the release of energy as particles lose kinetic energy and come closer together.
5. Conclude that the changes of state involving atoms or molecules gaining energy are sublimation and melting.