Adiabatic index of an ideal gas is 1.67. If universal gas constant R = 8.3 Joule/mol-K, value of Cv of the gas (in joule/mol-K) is
12.4
14.28
16.12
18.24
Cv=R(γ-1)=8·31·67-1 joule /mol-K=12.4Jmol-K