Thermodynamics - Result Question 4
4. An ideal gas goes from state $A$ to state $B$ via three different processes as indicated in the $P-V$ diagram:
[2012M]
If $Q_1, Q_2, Q_3$ indicate the heat a absorbed by the gas along the three processes and $\Delta U_1, \Delta U_2$, $\Delta U_3$ indicate the change in internal energy along the three processes respectively, then
(a) $Q_1>Q_2>Q_3$ and $\Delta U_1=\Delta U_2=\Delta U_3$
(b) $Q_3>Q_2>Q_1$ and $\Delta U_1=\Delta U_2=\Delta U_3$
(c) $Q_1=Q_2=Q_3$ and $\Delta U_1>\Delta U_2>\Delta U_3$
(d) $Q_3>Q_2>Q_1$ and $\Delta U_1>\Delta U_2>\Delta U_3$
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Answer:
Correct Answer: 4. (a)
Solution:
- (a) Initial and final condition is same for all process
$\Delta U_1=\Delta U_2=\Delta U_3$
from first law of thermodynamics
$\Delta Q=\Delta U+\Delta W$
Work done
$\Delta W_1>\Delta W_2>\Delta W_3$ (Area of P.V. graph)
So $\Delta Q_1>\Delta Q_2>\Delta Q_3$
