Find the temperature at which Kp = 4.00 for the reaction N2O4(g) <==> 2NO2(g). [Given: at 25°C, for NO2(g), ?H°f = 33.85 kJ/mol, S° = 240.46 J/mol·K; for N2O4(g), ?H°f = 9.66 kJ/mol, S° = 304.3 J/mol·K; assume that ?H° and ?S° are independent of temperature.]