ah ok, i considered that earlier but the other guy disagreed?
so because the pressure has decreased, the oxygen becomes less dense and expands, this makes it lose heat energy to work, therefore it cools down and is already at the lower pressure without being able to expand fully to the maximum...
ok so as the air expands, it will be converting its heat energy into work and therefore cool down, meaning temperature decreases and so the volume of oxygen in his tank will too?
because the pressure is lower at higher altitudes, so if the pressure varies, the temperature will vary in the same way.
So when the pressure lowers from 5x10^5 Pa to 1x10^5 Pa, then the temperature will lower?
ah wait, so would he have less because he won't be able to get the maximum volume as volume remains constant and there is less than the max volume of oxygen in the tank?