Question

Question #cdd5a

Answer 1

In the first reaction, the oxidation state of Cl in HCL is -1 and it changes to 0 in the free form of `Cl_2`. Hence it lost electrons and so was reduced.
Similarly the oxidation state of Mn in `MnO_2` is 4+ and this becomes 2+ in `MnCl_2` so the Mn gained electrons and was reduced.
By definition, HCL is then the oxidizing agent and `MnO_2` is the reducing agent.

A similar analysis may be applied in the second reaction to show that since `Zn -> Zn^(2+) and H^+->H_2`, it means that Zn was oxidized since it lost electrons, and H was reduced since it gained electrons. (Cl is a spectator ion here as its oxidation state does not change).
So then by definition, Zn is the reducing agent and HCL is the oxidizing agent.