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

Answer

D

Explanation

Total internal energy of system:
`U = U_("oxygen") + U_("argon")`
`U = n_(1)f_(1)/2 RT + n_(2)f_(2)/2 RT`
Degree of freedom is `f_(1) = 5` (for Oxygen) and `f_(2) = 3` (for Argon)
`U = 2(5/2)RT + 4(3/2) RT`
`U = 5RT + 6RT`
U = 11 RT