Correct option (d) 6 J
Explanation:
According to first law of thermodynamics,
δQ = δU+δW
Along the path adc Change in internal energy,
δU1 = δQ1 - δW1
= 50 J - 20 J = 30 J
Along the path abc Change in internal energy,
δU2 = δQ2 - δW2; δU2 = 36 J - δW2
As change in internal energy is path independent.