In a closed flask at 600 K, one mole of $$X_2Y_4(g)$$ attains equilibrium as given below : $$$X_2Y_4(g) \rightleftharpoons 2XY_2(g)$$$ At equilibrium, 75% $$X_2Y_4(g)$$ was dissociated and the total pressure is 1 atm. The magnitude of $$\Delta_r G^{\ominus}$$ (in kJ mol$$^{-1}$$) at this temperature is __________. (Nearest Integer) (Given : R = 8.3 J mol$$^{-1}$$ K$$^{-1}$$; ln 10 = 2.3, log 2 = 0.3, log 3 = 0.48, log 5 = 0.69, log 7 = 0.84)