Kinetic Theory - Result Question 24
24. A gas mixture consists of 2 moles of $O_2$ and 4 moles of Ar at temperature T. Neglecting all vibrational modes, the total internal energy of the system is :-
(a) $15 RT$
(b) $9 RT$
(c) $11 RT$
(d) $4 RT$
[2017]
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Answer:
Correct Answer: 24. (c)
Solution:
- (c) Internal energy of the system is given by $U=\frac{f}{2} nRT$ Degree of freedom
$F _{\text{diatomic }}=5$
$f _{\text{monoatomic }}=3$
and, number of moles
$n(O_2)=2$
$n(Ar)=4$
$U _{\text{total }}=\frac{5}{2}(2) RT+\frac{3}{2}(4) RT=11 RT$
