Which of the following is a pressure compounded turbine?

For a compressible fluid, sonic velocity is

A simple impulse turbine expands steam frictionlessly from $$12$$ bar, $${250^0}C$$ with an enthalpy of $$2935$$ $$kJ/kg$$ to an enthalpy of $$2584$$ $$kJ/kg$$ at $$0.1$$ bar. Assuming that the nozzle makes an angle of $${20^0}$$ with the blade motion, and that the blades are symmetrical, find the blade velocity that produces maximum efficiency for a turbine speed of $$3600$$ rev/min. assume that the steam enters the nozzle with negligible velocity.