Answer: When a gas changes to a liquid, the molecules in the gas lose some of their kinetic energy and their molecular attraction increases.
Step-by-step explanation:
In a gas, the molecules are moving around rapidly and colliding with each other and with the walls of the container. These collisions create pressure, and the average kinetic energy of the molecules is high. However, when the gas cools down, the average kinetic energy of the molecules decreases, and they move around more slowly.
As the gas cools down further, the molecules start to come closer together, and the intermolecular attractive forces become more important. Eventually, the attractive forces between the molecules become strong enough to overcome the kinetic energy of the molecules, and the gas condenses into a liquid.
In a liquid, the molecules are still in motion, but they are much closer together and have much lower average kinetic energy than in a gas. The attractive forces between the molecules are strong enough to keep them close together in a fixed volume, but not so strong that they are unable to move around freely.