Fact 1: Heating salt water causes the water to evaporate while the salt remains.

Fact 2: Evaporation is the change of state from a liquid to a gas.

Given the two facts above, answer the question "Heating salt water causes the water to do what while the salt remains?" with the following options: 
- change into a solid
 - freeze
 - change into a liquid
 - rapid expansion
 - flow of electrons
 - change into a gas
 - chemical reaction
 - It gets heated up


 

      change into a gas   