∆UAB=40J as process is isochoric. ∆UBC=+50(WBC=−50J) UC=UA+∆UAB+∆UBC=1650 For CA process, QCA=−60J ∆UCA+WCA=−60 −90+WCA=−60 ⇒WCA=+30J The graph given is inconsistent with the statement BC may be adiabatic and CA cannot be like isobaric as shown, as increasing volume while rejecting heat at same time.