For the given reactions Sn ^ 2 + + 2 e ^ - → Sn Sn ^ 4 + + 4 e ^ -...

(i) ${Sn}^{2 +} + 2{e}^{-} ⟶ Sn{E}_{1}^{0} = - 0 . 14V$

${\Delta G}_{1}^{0} = - 2F\left(- 0 . 14\right)$

(ii) $$\begin{array}{ll}{Sn}^{4 +} + 4{e}^{-} ⟶ Sn{E}_{2}^{0} = + 0 . 010V \\ {\Delta G}_{2}^{0} = - 4F\left(+ 0 . 010\right)\end{array}$$

Target ${Sn}^{4 +} + 2{e}^{-} ⟶ {Sn}^{2 +}{E}_{3}^{0} =$?

${\Delta G}_{3}^{0} = - 2F\left[{E}_{3}^{0}\right]$

Target Eq.=Eq. ii - Eq. i

$- 2F\left({E}_{3}^{0}\right) = - 4F\left(0 . 010\right) - \left(- 2F\left(- 0 . 14\right)\right)$

${E}_{3}^{0} = \dfrac{4 \times 0 . 010 + 2 \times 0 . 14}{2} = 0 . 16V = 16 \times {10}^{- 2}V$