Introduction to Reaction Mechanisms Practice Test

A student proposes the following mechanism for the net reaction $\mathrm{ClO^-(aq) + 2,I^-(aq) + 2,H^+(aq) \rightarrow I_2(aq) + Cl^-(aq) + H_2O(l)}$:

Step 1: $\mathrm{ClO^-(aq) + H^+(aq) \rightarrow HOCl(aq)}$

Step 2: $\mathrm{HOCl(aq) + I^-(aq) \rightarrow HOI(aq) + Cl^-(aq)}$

Step 3: $\mathrm{HOI(aq) + I^-(aq) + H^+(aq) \rightarrow I_2(aq) + H_2O(l)}$

Which species acts as an intermediate in this mechanism?

A student proposes the following mechanism for the overall reaction $\text{H}_2(g)+\text{I}_2(g)\rightarrow 2\text{HI}(g)$:

Step 1: $\text{I}_2(g)\rightarrow 2\text{I}(g)$

Step 2: $\text{H}_2(g)+\text{I}(g)\rightarrow \text{HI}(g)+\text{H}(g)$

Step 3: $\text{H}(g)+\text{I}(g)\rightarrow \text{HI}(g)$

Which species is an intermediate in the mechanism?