21. Consider the following reaction at 25℃: 2NO2(g) →N2O4(g). The values of △Ho and △Soare -58.03 kJ/mol and -176.6(J/K)(mol), respectively. Assuming △H^{o and  △So  are temperature independent, the calculated value of K at 100℃ is__________ .
(A) 2.54
(B) 0.0789
(C)0.789
(D) 7.89
(E)0.2543}