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

Total internal energy of system:
` = U_("oxygen") + U_("Argon") = mu_(1) f_(1)/2 RT + mu_(2)f_(2)/2 RT`
` = 2(5/2)RT + 4(3/2)RT = 5RT + 6RT = 11 RT`
[As `f_(1) = 5` (for oxygen) and `f_(2) = 3` (for Argon)]