In view of the signs ${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{G}}^{\circ }$ of for the following reactions

$\begin{array}{l}{\mathrm{PbO}}_2+\mathrm{Pb}\to 2\mathrm{PbO};\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{\Delta }}_{\mathrm{t}}{\mathrm{G}}^{\circ }<0\\ {\mathrm{SnO}}_2+\mathrm{Sn}\to 2\mathrm{SnO};\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{\Delta }}_{\mathrm{T}}{\mathrm{G}}^{\circ }>0\end{array}$

Which oxidation states are more characteristic for lead and tin?

${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{G}}^{\circ }<0$ implies that the reaction is feasible. Thus, the more characteristic oxidation state of lead is +2.

 ${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{G}}^{\circ }>0$ implies that the reaction is not feasible. Thus, the more characteristic oxidation state of tin is +4.