For the first-order reaction 1/2 NO4(g) NO(g); DH = 28.6 kJ the rate constant is k = 9.29 104 s-1 at -20C, and the activation energy is 53.7 kJ/mol. What is the rate constant at 21C? O 1.08 105 S-1 O 9.29 104 S-1 O 1.74 105 S-1 O 3.27 106 S-1 O. 4.94 104 S-1