Standard entropies of X2, Y2 and XY3 are given below the reaction1/2X2+3/2Y2⇌XY3; ΔH∘=−30kJmol−1S∘ 60 40 50JK−1mol−1At what temperature, reaction would be in equilibrium?

Reaction will be in equilibrium whenΔG∘=0 But  ΔG∘=ΔH∘−TΔS∘ Then, T=ΔH∘ΔS∘ΔH∘=−30kJmol−1ΔS∘=S∘XY3−12S∘X2+32S∘Y2=50−12×60+32×40=50−[30+60]=−40JK−1mol−1T=−30×1000Jmol−140KK−1mol−1=750KHence, at 750 K, reaction would be in equilibrium.