Final answer:
When gas condenses into a liquid, the particles slow down and come closer together due to decreased kinetic energy and increased intermolecular forces.
Step-by-step explanation:
According to the model of gas particles, when a gas condenses into a liquid, option B is correct: Particles slow down and come closer together. As the temperature decreases, the particles lose kinetic energy, and the forces of attraction between them become more significant. This reduction in kinetic energy results in a decrease in the movement of the particles, and they come closer together, leading to the formation of a liquid. Understanding these changes in particle behavior during phase transitions provides insights into the behavior of matter under different conditions, contributing to our understanding of thermodynamics and phase changes.