Consider the values of reduction potential:
\(\mathrm{Co}^{3+}+e^{-} \rightarrow \mathrm{Co}^{2+} ; E^{\circ}=+1.81 \mathrm{~V}\)
\(\mathrm{~Pb}^{4+}+2 e^{-} \rightarrow \mathrm{Pb}^{2+} ; E^{\circ}=+1.67 \mathrm{~V}\)
\(\mathrm{Ce}^{4+}+e^{-} \rightarrow C e^{3+} ; E^{\circ}=+1.61 \mathrm{~V}\)
\( \mathrm{Bi}^{3+}+3 e^{-} \rightarrow \mathrm{Bi} ; E^{\circ}=+0.20 \mathrm{~V}\)
The oxidizing power of the species will increase in the order of:
1. | \(C o^{3+}<C e^{4+}<B i^{3+}<P b^{4+}\) |
2. | \(\mathrm{Co}^{3+}<P b^{4+}<C e^{4+}<B i^{3+}\) |
3. | \(C e^{4+}<P b^{4+}<B i^{3+}<C o^{3+}\) |
4. | \(B i^{3+}<C e^{4+}<P b^{4+}<C o^{3+}\) |