Dry saturated steam enters a friction-less adiabatic nozzle with negligible velocity at a temperature of $${300^ \circ }C.$$ It is expanded to a pressure of $$5000$$ $$kPa.$$ The mass flow rate is $$1$$ $$kg/s$$. Calculate the exit velocity of steam.

A heat reservoir at $$900$$ $$K$$ is brought into contact with the ambient at $$300$$ $$K$$ for a short time. During this period $$9000$$ $$kJ$$ of heat is lost by the heat reservoir. The total loss in availability due to this process is

Constant pressure lines in the super-heated region of the Mollier diagram will have

Consider a refrigerator and a heat pump working on the reversed Carnot cycle between the same temperature limits. Which of the following is correct?