Apropane torch is lit inside a hot air balloon during preflight preparations to inflate the balloon. which condition of the gas remains constant? volume pressure temperature

The correct answer is Pressure.

As the propane torch is lit inside the hot air balloon, the volume of the gas increases as the temperature increases. Though there is an arrangement for the extra gas to move out through a hole. And, as the temperature increase the density of the gas decreases to overall make the pressure of the gas constant. Thus, constant pressure is the condition.