3 moles of mono atomic ideal gas are mixed with 2 moles of diatomic ideal gas. Then the ratio of  CPCV of the mixture is

(2)'γm'  =CPCV  for  mono  atomic  gas  =3+23=53   Cp1=5R2, Cv1=3R2'γd'  =CPCV  for  dia  atomic  gas  =5+25=75      Cp2 =7R2 , Cv2= 5R2γ for the mixture n1Cp1+n2Cp2n1Cv1+n2Cv2=35R2+27R23 3R2+2 5R2=15+149+10=2919