A gas cylinder contains 2 cubic metres of air at a pressure of 700 atmospheres at room temperature. Calculate the volume of air in the cylinder at one atmospheric pressure at room temperature. If the air is drawn from the cylinder at the rate of 15 litres/minute, how lonf will the cylinder last? I have no idea how to work this out. A friend and I thought it may have to do with mass density D=m/V but then we just got more confused. If you would be able to help, that would be great. If you could show calculations and explaination (or just calculations if it's too much ) much appreciated.