Neet Solved Paper 2015 Question 21
Question: One mole of an ideal diatomic gas undergoes a transition from A to B along a path AB as shown in the figure The change in internal energy of the gas during the transition is
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Options:
A) 20 kJ
B) -20 kJ
C) 20 J
D) -12 kJ
Show Answer
Answer:
Correct Answer: B
Solution:
For a diatomic gas, $ C _{V}=\frac{5}{2}R $
The change in internal energy of gas in the transition from A to B is $ \Delta U=nC _{v}dT $
$ =n( \frac{5R}{2} )(T _{B}-T _{A}) $
$ =nR\frac{5}{2}( \frac{p _{B}V _{B}}{nR}\frac{p _{A}V _{A}}{nR} ) $
$ =\frac{5}{2}(2\times 10^{3}\times 6-5\times 10^{3}\times 4) $
$ =\frac{5}{2}\times (-8\times 10^{3}) $ $ =-\frac{4\times 10^{4}}{2}=-20KJ $
