Question

Which one of the following pairs of equations describes an irreversible heat engine?                                                                            

      (a) $\oint \delta Q> 0and\oint \frac{\delta Q}{T}< 0$ 

      (b) $\oint \delta Q< 0and\oint \frac{\delta Q}{T}< 0$ 

      (c) $\oint \delta Q> 0and\oint \frac{\delta Q}{T}> 0$ 

      (d) $\oint \delta Q< 0and\oint \frac{\delta Q}{T}> 0$