For the reaction
2NO2(g)→2NO(g)+O2(g)
which of the following correctly relates the instantaneous reaction rates expressed as concentration changes?
a) rate=−dtd[NO2]=2dtd[NO]=2dtd[O2]
b) rate=−21dtd[NO2]=21dtd[NO]=dtd[O2]
c) rate=−21dtd[NO2]=dtd[NO]=21dtd[O2]
d) rate=−dtd[NO2]=dtd[NO]=dtd[O2]