Helium at 68 degrees Farenheit and 14.7 psia in a large tank flows steadily and isentropically thorugh a converging nozzle to a reciever pipe. The cross-sectional area of the throat of the converging passage is 0.05 ft^2. Determine the mass flow rate through the duct if the reciever pressure is A.) 10 psia, B.) 5 psia. Sketch temperature-entropy diagrams for situations A and B.