For the reaction CO(g) + Cl2(g) → COCl2(g), three possible rate-determining elementary steps are proposed.
I. CO + Cl2 → COCl + Cl (bimolecular)
II. Cl + Cl2 → Cl3 (bimolecular)
III. CO + Cl + Cl2 → COCl2 + Cl (termolecular)
Which sequence correctly ranks the steps from MOST likely to LEAST likely to occur under the same conditions?
a) I>II>III
b) II>I>III
c) III>II>I
d) II>III>I