Two moles of helium gas is mixed with three moles of hydrogen molecules (taken to be rigid) what is the molar specific heat of micture of constant volume? `(R=8.3JmolK)`

Options

A. 15.7 J/mol K
B. 19.7 J/mol K
C. 17.4 J/mol K
D. 21.6 J/mol K

Answer

C

Explanation

`U=U_1+U_2," "(n_1+n_2)Cv triangleT=n_1cv_1triangleT+n_2Cv_2triangleT`
`Cv=(n_1Cv_1-1+n_2Cv_2)/(n_1+n_2)= (2xx(3)/(2)R+3xx(5)/(2)R)/(5)=2.1R`.