It was used up. It condensed. It was absorbed by the heat. It turned into water vapor.
I gave my students this multiple choice question: A student put 200 milliliters (mL) of water into a pot, sets the pot on a burner, and heats the water to boil. When the pot is taken off the burner, it contains only 180 milliliters (mL) of water. What happened to the rest of the water?

Only one answer is correct among these 4 choices:
- It was used up.
- It condensed.
- It was absorbed by the heat.
- It turned into water vapor.

Could you tell me which one is correct?

It turned into water vapor.