An ideal monoatomic gas is carried around the cycle ABCDA as shown in the figure. The efficiency of the cycle is

Efficiency  = work doneheat absorbed= area  of  the  PV diagramheat  absorbed         Heat absorbed in AB and BCQAB = nCvdT  =  3R2n3To−To = 6RTo2(at constant volume it pressure increases to 3 times temperature also becomes 3 times)  TB=3TAQBC = nCpdT = 5R2n6To−3To =15RTo2(at constant pressure if volume becomes double temperatureis also doubles)  TC=2TB=6TAEfficiency = 2poVo21RTon2 = 4nRTo21nRTo =421 ,% efficiency=421 ×100=19%