As the temperature of the gas in a balloon increases, what happens?
The volume of the balloon expands..........
Volume is a state function of temperature and pressure, given a specific amount of (i.e. no. of moles). Hot air balloons (which you don't tend to see so much of these days, maybe I am in the wrong country) rely on this principle, in that by displacing enough air at normal temperature they can be sufficiently buoyant to lift a basket, gas tanks, and burner, and with a couple of balloonists.