Evaporation: Escape of Energetic Molecules

Steps:

• Identify the process: The description involves molecules leaving a liquid surface due to high energy.
• Recall phase changes: Evaporation converts liquid to gas at the surface without boiling.
• Match the mechanism: Only evaporation features selective escape of faster, more energetic molecules.
• Eliminate mismatches: Other options describe different phase transitions or energy transfers.

Why B is correct:

• Evaporation is defined as the surface process where molecules with sufficient kinetic energy overcome intermolecular forces to enter the gas phase.

Why the others are wrong:

• A. Condensation: Gas molecules collide and lose energy to join the liquid surface.
• C. Melting: Solid particles gain energy to become liquid, not escape from a liquid.
• D. Radiation: Emission of electromagnetic energy, unrelated to molecular movement from liquids.

Final answer: B