For the following questions answer them individually
The heat transfer Q, the work done W and the change in internal energy U are all zero in the case of
A reversible engine operates between temperatures $$T_{1}$$ and $$T_{2}$$ . The energy rejected by this engine is received by a second reversible engine at temperature $$T_{2}$$ and rejected to a reservoir at temperature $$T_{3}$$ If the efficiencies of the engines are same then, the relationship between $$T_{1}$$ , $$T_{2}$$ and $$T_{3}$$ is given by
Efficiency of a Carnot engine is 75%. If the cycle direction is reversed, COP of the reversed Carnot cycle is
