For the gas-phase reaction ClO+NO→Cl+NO2, a mechanism must be written that satisfies two constraints:
• Every elementary step must be bimolecular.
• NO must act as a catalyst, appearing unchanged in the net equation.
Which of the following elementary steps would violate at least one of these constraints if included in the mechanism?
a) 2ClO→Cl2+O2
b) ClNO2→Cl+NO2
c) ClO+NO→ClNO2
d) ClNO+ClO→2Cl+NO2