The decomposition of hydrogen peroxide in the presence of iodide ion is believed to occur via this mechanism.
H2O2(aq) + I - (aq) → H2O(l) + IO - (aq)
H2O2(aq) + IO - (aq) → H2O(l) + O2(g) + I - (aq)
In this mechanism, I - (aq) is
(A) a catalyst.
(B) a reactant in the overall reaction.
(C) the activated complex.
(D) a product of the overall reaction.