What happens to the density of the air in the balloon as it is heated?
Also, based on this question.... What would be the Independent variable, Depended Variable, controlled Variable.
As you heat air molecules, they gain more energy and move farther apart which results in less density.
control would be the amount of air in the balloon because that doesn't change since air isn't leaving or entering the balloon.
Indep. would be the heat
dep. would be the density because it depends on the amount of heat added.