A reversible cycle executed by 1 mole of an ideal gas with p = 2.5 and v = 1.5. The following three steps are involved:

Step (1 2): Starting at state 1( 700, 1.5), the gas is cooled at constant pressure to 350

Step (2 3): From state 2 (350 K and 1.5 bar), the gas is isothermally compressed to state 3

Step (3 1): The gas returns to state 1 along a path of which PT=constant

Calculate the thermal efficiency of this cycle process and the entropy change for each individual step.