The P-V diagram of a system undergoing thermodynamic transformation is shown in the given figure. The work done on the system in going from A\(\rightarrow\)B\(\rightarrow\)C is 50 J and 20 cal heat is given to the system. The change in internal energy between A and C is : 

134 J

Heat given : \(\Delta\) Q = 20 cal = 20 x 4.2 = 84 J

Work done : \(\Delta\) W = - 50 J ... (as the process is anticlockwise)

By First Law of Thermodynamics : \(\Delta U = \Delta Q - \Delta W\)

\(\Delta U = 84 - (-50) = 134 J\)