Final answer:
The best procedure to demonstrate condensation and evaporation in the water cycle experiment is to decrease the temperature to show condensation, and increase it to show evaporation. Evaporation occurs with added heat, while condensation happens as vapor cools down.
Step-by-step explanation:
To demonstrate the difference between condensation and evaporation in an experiment that shows the important steps of the water cycle, the correct procedure is option B: To show condensation, the lab partners must decrease the temperature within the cycle; to show evaporation, they must increase the temperature.
Evaporation is a process where liquid water turns into vapor or gas. It occurs when molecules at the surface of the liquid gain enough kinetic energy to break free from the attraction of other liquid molecules and enter the air. An increase in temperature boosts this process because it raises the kinetic energy of the molecules.
Condensation, on the other hand, happens when water vapor in the air loses energy and transforms back into liquid. This typically occurs on cold surfaces because cooling the vapor decreases its kinetic energy, causing the molecules to come closer together and coalesce into liquid form.