34. Perfect diatomic gas, containing a quantity of substance ν = l mol and pressurized p1 = 0,1 MPa at a temperature of T1 = 300 K, is heated at constant volume to a pressure p2 = 0,2 MPa. After that, the gas isothermally expanded to the initial pressure, and then the isobaric was compressed to the initial volume V1. Plot the cycle. Determine the temperature T gas characteristic points of the cycle and the thermal efficiency η.