Textbook Problem

. In each of the following reactions, identify which element is being oxidized and which is being reduced by assigning oxidation numbers.

a. $\text{Fe}\left(\text{s}\right)+{\text{CuSO}}_{\text{4}}\left(\text{aq}\right)\to {\text{FeSO}}_{\text{4}}\left(\text{aq}\right)+\text{Cu}\left(\text{s}\right)$   b. ${\text{Cl}}_{\text{2}}\left(\text{g}\right)+\text{2NaBr}\left(\text{aq}\right)\to \text{2NaCl}\left(\text{aq}\right)+{\text{Br}}_{\text{2}}\left(\text{l}\right)$   c. $\text{3CuS}\left(\text{s}\right)+{\text{8HNO}}_{\text{3}}\left(\text{aq}\right)\to {\text{3CuSO}}_{\text{4}}\left(\text{aq}\right)+\text{8NO}\left(\text{g}\right)+{\text{4H}}_{\text{2}}\text{O}\left(\text{l}\right)$ .

d. $\text{2Zn}\left(\text{s}\right)+{\text{O}}_{\text{2}}\left(\text{g}\right)\to \text{2ZnO}\left(\text{s}\right)$