You are presented with the question "What happens when liquids are heated?" and the following answer choices: 
- Evaporation
 - chemical reaction
 - air is cooled
 - food is chilled
 - It expands
 - gas bubbles burst
 - flow of electrons
 - bubbles reduce

Now knowing that boiling is when liquids are heated above their boiling point and lots of gas bubbles burst over the boiling lakes' surface, choose the best answer.


 

      gas bubbles burst   