(b) Temperature change ΔT is same for all three processes A→B;A→C and A→DΔU=nCv​ΔT= same EAB​=EAC​=EAD​ Work done, W=P×ΔVAB→ volume is increasing ⇒WAB​>0AD→ volume is decreasing ⇒WAD​<0AC→ volume is constant ⇒WAC​=0