Alarge chamber contains air at 80 psia and 600 r at zero velocity. the air enters a converging- diverging nozzle which has an area ratio (exit/throat) of 3.0 a) what pressure must exist in the receiver for the nozzle to operate at its first critical point? the flow will reach sonic at the throat then decelerate to subsonic conditions at the exit b) what should the receiver pressure be for operating at the third critical point where supersonic flow exits the nozzle? if operating at the third critical point, what are the density and velocity of the air at the nozzle exit plane?