Question

before: solid
after: liquid

1. a student left a sealed jar of water outside her home. water can be a solid, liquid, or gas. when she put it outside, the water was a solid. twelve hours later, the water had changed phase and was a liquid. what happened to the water molecules?

a before the student left, the molecules were moving in place.
after, the molecules were moving around each other.
b before the student left, the molecules were moving around each other.
after, the molecules were moving away from each other.
c before the student left, the molecules were moving around each other.
after, the molecules were moving in place.
d before the student left, the molecules were moving away from each other.
after, the molecules were moving around each other.

Explanation:

In the solid state (ice), water molecules are locked in a fixed structure and only vibrate in place. When melting into liquid water, molecules gain energy, break free from the fixed structure, and move around each other. Option a matches this behavior, while other options describe incorrect molecular motion for the given phase change.

Answer:

a. Before the student left, the molecules were moving in place.
After, the molecules were moving around each other.