question_answer

In the given figure, the initial and final states of a gas are shown by points \[i\]and \[f.\] The internal energy of the gas at i is 10 J. For the path ibf; dQ = 50 J and dW = 20 J. For the path ibf, if dQ = 36 J the value of dW will be equal to

A)  4 J                                         

B)  12 J

C)  18 J                                       

D)  6 J

Correct Answer: D

Solution :

                                  For path \[iaf\]                                 \[dU=dQ-dW\]                                 \[=50-20=30J\]                 For path ibf                                 \[dU=-30\,J\]                                 \[30=36-dW\]                                 \[30=36-dW\]                                 \[dW=6\,J\]