What happens to the kinetic energy of particles during condensation?

• A. Increases as gas particles speed up to form a liquid.
• B. Kinetic energy remains the same as gas condenses.
• C. Kinetic energy decreases as gas particles slow and join to form a liquid.
• D. Kinetic energy becomes zero when condensation occurs.

Answer: (C)

During condensation, gas molecules must slow down enough to be held together by intermolecular forces as they form a liquid. Kinetic energy is tied to how fast the particles move, so as they slow, the average kinetic energy decreases. The energy released when these attractions form leaves the system as heat to the surroundings, so the gas cools while it condenses. The molecules don’t stop moving entirely—they just have less kinetic energy than in the gaseous state.