Solve this following


A gas mixture consists of 3 moles of oxygen and 5 moles of argon at temperature $\mathrm{T}$. Assuming the gases to be ideal and the oxygen bond to be rigid, the total internal energy (in units of RT) of the mixture is :


  1. 11

  2. 15

  3. 20

  4. 13

Correct Option: , 2


$\mathrm{u}=\frac{\mathrm{f}_{1} \mathrm{n}_{1} \mathrm{RT}}{2}+\frac{\mathrm{f}_{2} \mathrm{n}_{2} \mathrm{RT}}{2}$

$\mathrm{u}=\frac{5}{2} \times 3 \mathrm{RT}+\frac{3 \times 5 \mathrm{RT}}{2}=15 \mathrm{RT}$


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