chemical reaction Condensation A physical change Evaporation
I gave my students this multiple choice question: A drain cleaner consists of sodium hydroxide and aluminum. When the drain cleaner is added to water, bubbles of hydrogen are produced, and the solution becomes very hot. Which of these best describes what happens to form the bubbles when the cleaner is added to water? F

Only one answer is correct among these 4 choices:
- chemical reaction
- Condensation
- A physical change
- Evaporation

Could you tell me which one is correct?

chemical reaction