a A perfect gas (gamma = 1.9) enters a converging-diverging nozzle with a Mach number of 0.98 and local pressure and temperature values of 490 kPa and 570 K, respectively. The nozzle throat area is 6.5 * 10^-4 m^2 and the nozzle exit area is 26*10^-4 m^2. The nozzle exit pressure is 170 kPa. Verify that the back pressure is such that a shock occurs. a) What are the values of the mach number and stream temperature at the exit? b) At what area does the shock occur