What happens to the molecules within a gas when the gas condenses? A. They gain energy. B. They lose energy. C. They drift apart. D. They move faster.

The correct answer is B. They lose energy.<br /><br />**Explanation:**<br /><br />Condensation is the process where a gas transitions to a liquid state. For this to happen, the molecules in the gas must slow down and move closer together. This decrease in molecular speed corresponds to a decrease in kinetic energy, meaning the molecules lose energy. The energy lost is often released as heat.<br /><br />* **A. They gain energy:** This is the opposite of what happens during condensation. Gaining energy would make the gas molecules move faster, potentially leading to a phase change in the other direction (like boiling).<br /><br />* **C. They drift apart:** This happens during evaporation or when a gas expands, not during condensation.<br /><br />* **D. They move faster:** Again, this is the opposite of what happens during condensation. Increased speed means increased kinetic energy, which is associated with phase changes like evaporation or boiling.<br />