Fact 1: If gas is heated then that gas will expand.

Fact 2: If a material is heated, it expands and the density decreases.

Given the two facts above, answer the question "What happens to the density of a gas when heated?" with the following options: 
- stays constant
 - Temperature
 - energy
 - Energy.
 - decreases
 - nothing
 - Evaporation
 - increases


 

     decreases    