According to the first law of thermodynamics,
∆U = q + W (i)
Where,
∆U = change in internal energy for a process
q = heat
W = work Given,
q = + 701 J (Since heat is absorbed)
W = –394 J (Since work is done by the system) Substituting the values in expression (i), we get
∆U = 701 J + (–394 J)
∆U = 307 J
Hence, the change in internal energy for the given process is 307 J.