∆U=q+w ∆U will be same for path 1,2 and 3 because it depends on initial and final positions and they are same for all of them. Work done is area under p∆V curve. Greater the area more will be the work done. Work is a path function. Since the area under p∆V curve is largest for path 3 and smallest for path 1, therefore, w1<w2<w3.