The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data.

H2O2 + I - = H2O + IO - (slow)
H2O2 + IO - = H2O + O2 + I - (fast)

Which one of the following statements is false? Choose answer (E) if more than one or none are false.

a. The reaction is first order with respect to H2O2.
b. The reaction is first order with respect to I -
c. I - is a catalyst.
d. IO - is an intermediate.
e. More than one the above statements is false (or none of the statements are false).

To determine which statement is false, let's analyze each statement one by one:

a. The reaction is first order with respect to H2O2.
To determine the order with respect to a particular reactant, we look at the rate equation for the overall reaction. In this case, the rate-determining step is the slow step: H2O2 + I- = H2O + IO-. Since the concentration of H2O2 appears only in the slow step, we can conclude that the reaction is indeed first order with respect to H2O2. Therefore, statement (a) is true.

b. The reaction is first order with respect to I-.
Similar to statement (a), we look at the rate equation to determine the order with respect to I-. In the slow step, the concentration of I- appears, so we can conclude that the reaction is first order with respect to I-. Hence, statement (b) is true.

c. I- is a catalyst.
A catalyst is a substance that is involved in the reaction but remains unchanged at the end of the reaction. In this mechanism, I- is not produced or consumed; it appears in both the reactants and the products of the slow step. Therefore, I- does not meet the criteria for a catalyst, so statement (c) is false.

d. IO- is an intermediate.
An intermediate is a species that is formed in one step of a reaction and consumed in a subsequent step. In this mechanism, IO- is formed in the slow step (H2O2 + I- -> H2O + IO-) and consumed in the fast step (H2O2 + IO- -> H2O + O2 + I-). Since IO- is formed and consumed during the reaction, it can be classified as an intermediate. Hence, statement (d) is true.

Based on the analysis, the false statement is (c) "I- is a catalyst." Therefore, the answer is (c).