(a) Is it true that if the mass flow rate of a gas is low, say 2g/s (grams per second), the friction losses and other losses in the piping will be negligible? (b) If it is true that losses in the piping are negligible, is it the Euler's dimensionless number that we can use to prove this? (c) If it is the Euler's dimensionless number, please indicate the proof. If it is not Euler, which one is it? (d) Is it true that at such low mass flow rates, the main driving force is the vapour pressure of the gas?