A gas mixture consists of 2 moles of oxygen and 4 moles of argon at temperature T. Neglecting all vibrational modes, the total internal energy of the system is

Options

A. 4 RT
B. 15 RT
C. 9 RT
D. 11 RT

Answer

D

Explanation

For Oxygen , no of moles `n_(1) =2` ,
no. Of degree of freedom per molecule, `f_(1) = 5`
For Argon, no.of moles , `n_(2)=4`
no.of degree of freedom per molecule, `f_(2) =3`.
Total internal energy of the system is
`U = n_(1)(f_1)/(2)RT + n_(2)(f_2)/(2) RT`
`= 2 xx 5/2 RT + 4 xx 3/2 RT = 5 RT + 6RT`
`=11RT`.