Answer
See explanation.
Work Step by Step
Heat flow, Q in ab. The work done,W is zero because $\Delta V = 0$
$Q = ΔU +0$
$Q = (240 J - 150 J )$
$Q = 90J$ The heat is absorbed into the system
Heat flow, Q in bc
$Q = ΔU +W$
$Q = (680 J - 240 J) +450 J$
$Q = 440J + 450J$
$Q = 890 J$ The heat is absorbed to the system
Heat flow, Q in ad
$Q = ΔU +W$
$Q = (330J - 150J ) +120 J $
$Q = 180 J + 120 J$
$Q = 300 J $ The heat is absorbed to the system
Heat flow, Q in dc where w = 0
$Q = ΔU +W$
$Q = (680J - 330 J) + 0$
$Q = 350 J$ The heat is absorbed to the system
