You are presented with the question "What does boiling change a liquid into?" and the following answer choices: 
- oil
 - heat
 - SO2
 - salt
 - ice
 - solid
 - water
 - gas

Now knowing that heating a liquid can be used to identify that liquid 's boiling point and because at the boiling point of water, there are molecules that are a gas and that are a liquid, choose the best answer.


 

        gas 