Oxygen is absorbed from the air. Heat is radiating in the liquid. The boiling point has been reached. Molecular stability in the liquid is increasing.
I gave my students this multiple choice question: What has occurred when bubbles form in a liquid that is being heated?

Only one answer is correct among these 4 choices:
- Oxygen is absorbed from the air.
- Heat is radiating in the liquid.
- The boiling point has been reached.
- Molecular stability in the liquid is increasing.

Could you tell me which one is correct?

The boiling point has been reached.