Final answer:
When Kylie put the water into the freezer, the temperature dropped, and the water particles got colder, which means their kinetic energy decreased.
Step-by-step explanation:
The question you've asked is about how water particles change in temperature. When the temperature in a beaker of water goes from 50 Celsius to 10 Celsius because it was put in the freezer, the correct answer to how the water particles changed is: C) The water particles got colder.
As temperature is a measure of the average kinetic energy of the particles in a substance, lowering the temperature means the kinetic energy of the water particles decreases. The particles move slower and the overall energy of the system goes down. Temperature is crucial in these processes and understanding the relationship between temperature and particle movement is a key concept in Chemistry.