Identify each of the following as an oxidation or a reduction: (7.6)
a. $\mathrm{Zn}^{2+}(a q)+2 e^{-} \longrightarrow \mathrm{Zn}(s)$
b. $\mathrm{Al}(s) \longrightarrow \mathrm{Al}^{3+}(a q)+3 e^{-}$
c. $\mathrm{Pb}(s) \longrightarrow \mathrm{Pb}^{2+}(a q)+2 e^{-}$
d. $\mathrm{Cl}_{2}(g)+2 e^{-} \longrightarrow 2 \mathrm{Cl}^{-}(a q)$