1. The problem statement, all variables and given/known data An Astronaut on a spacewalk has an oxygen tank strapped to his suit. The oxygen in it is pressurised to 5 atmospheres (5x10^5 Pa), and the volume of the tank is 15 litres. a) The oxygen is pumped to his mouth at atmospheric pressure (1x10^5 Pa). What is the maximum volume of oxygen available to the astronaut at this pressure? b) What assumptions are made about the gas that allow us to perform this calculation? c) In reality, the astronaut would find that he had less oxygen available to him than calculated in part (a). Why would this be the case? (Problem Solving!) 2. Relevant equations 3. The attempt at a solution Help with question (c) please, I've put in the rest of the question for context too. I thought it may be that as he breathes more oxygen, the tank will become more space/air molecules than oxygen molecules and so there would be less oxygen, or that the cold temperature outside would could the tank and the gas, making the temperature decrease and therefore the volume decrease but i'm not sure after that?