What is the volume occupied? What is the volume occupied by 1 mole of gas at  $10^{−10}$ torr, the pressure inside an “ultra high vacuum” (UHV) chamber. 
How do I solve this problem without being given the temperature?
 A: Looking at the ideal gas equation $p V = \frac{f}{2} n R T$, you can see that the volume $V$ will be directly proportional to the temperature $T$. That makes sense intuitely: The gas molecules will possess higher momentum on average, so in order to maintain a constant pressure one has to adapt the "bump rate" into a given surface area of the container, as the individual impacts become more hostile. The only way to do that is to increase the volume of the container when temperature grows (so as to make impacts rarer per surface area). You have to know the temperature in order to answer this question.
A: Simple actually. If your not given the temperature in the problem, 
(1) you make a guess! You think of what an ideal temperature should be for such a system/experiment. If that's not convincing enough, it's time to get a bit more deeper! 
(2) Open up google, search for how UHV chambers are operated. This should provide you with articles that explain the setup in detail, which will definitely include the operable temperature somewhere!
This two step process makes sure you learn the most out of each problem of a similar type as yours. You get to improve your intuition, and also get to learn more about the subject matter. 
Best of LucK!
