A converging - diverging frictionless nozzle is used to accelerate an airstream emanating from a large chamber. The nozzle has an exit area of 30 cm^2 and a throat area of 15 cm^2. If the ambient pressure surrounding the nozzle is 101 kPa and the chamber temperature is 500 K, calculate the following:
A) Minimum chamber pressure to choke the nozzle
B) Mass flow rate for a chamber pressure of 400 kPa