Iodide is oxidized by hydrogen peroxide according to the following mechanism?

a)
H₂O₂ + I⁻ → H₂O + OI⁻ (slow) …… [1]
H⁺ + OI⁻ → HOI (fast) …… [2]
HOI + H⁺ + I⁻ → I₂ + H₂O (fast) …… [3]

[1] + [2] + [3], and cancel HOI and OI⁻ on the both sides. The equation for the overall reaction is :
H₂O₂ + 2H⁺ + 2I⁻ → 2H₂O + I₂


b)
Molecularity of the first step = 2
Molecularity of the second step = 2
Molecularity of the third step = 3


c)
Rate equation for the rate-determining step (the first step) :
Rate = k [H₂O₂] [I⁻]


d) The intermediates in this reaction are HOI and OI⁻.