Thermodynamics Question 135
Question: One mole of an ideal monoatomic gas is heated at a constant pressure of one atmosphere from $ 0^{o}C $ to $ 100^{o}C $ . Then the change in the internal energy is
[Pb. PMT 2001]
Options:
A) 6.56 joules
B) $ 8.32\times 10^{2} $ joules
C) $ 12.48\times 10^{2} $ joules
D) 20.80 joules
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Answer:
Correct Answer: C
Solution:
Change in internal energy is always equal to the heat supplied at constant volume. i.e.
$ \Delta U={{(\Delta Q)} _{V}}=\mu C _{V}\Delta T. $
For monoatomic gas $ C _{V}=\frac{3}{2}R $
Therefore $ \Delta U=\mu ( \frac{3}{2}R )\Delta T=1\times \frac{3}{2}\times 8.31\times (100-0) $
$ =12.48\times 10^{2}J $
