A gas mixture consists of 2 moles of oxygen and 4 moles of argon at temperature ‘T’. Neglecting all vibrational mode, the total internal energy of the system is

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

Solution:

Total Internal Energy of System = $U_{oxygen} + U_{argon}$

$\begin{array}{l} = μ \frac{f_{1}}{2} R T + μ_{2} \frac{f_{2}}{2} R T \\ (f = degree of fredom) \\ = 2 \frac{5}{2} R T + 4 \frac{3}{2} R T \\ = 5 R T + 6 R T \\ = 11 R T \end{array}$

$A s f_{1} = 5 (for oxygen) and f_{2} = 3 (for Argon)$

Therefore, the correct answer is (D).

Solution:

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