• # question_answer 15) A gas is taken along the path as shown in the figure. If heat supplied to the system is 20 J, then the change in the internal energy is A)  125 J                         B)  -10 JC)  10 J               D)  55 J

Here, V - P curve is given and not P - V. $W=-\frac{1}{2}[30+40\times {{10}^{3}}]\times 3\times {{10}^{-3}}=-105\,J$ Work is negative because the volume is decreasing From$dQ=dU+dW$ $\Rightarrow$$dU=(20+105)J=125\,J$ Hence, the correction option is [a].