Salt bridge contains :-

$\text{E°}$ for ${\mathrm{F}}_2+2e=2{\mathrm{F}}^{-}$ is $2·8 \mathrm{V},$ $\text{E°}$ for $\frac{1}{2}{\mathrm{F}}_2+\mathrm{e}={\mathrm{F}}^{-}$ is:

Electrode potential data are given below.

${\mathrm{Fe}}^{3+}\left(\mathrm{aqueous}\right)+{\mathrm{e}}^{-}⟶{\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right); {\mathrm{E}}^{\circ }=+0.77$

${\mathrm{Al}}^{3+}\left(\mathrm{aqueous}\right)+3{\mathrm{e}}^{-}⟶\mathrm{Al}\left(\mathrm{s}\right); {\mathrm{E}}^{\circ }=-1.66 \mathrm{V}$

${\mathrm{Br}}_2\left(\mathrm{aqueous}\right)+2{\mathrm{e}}^{-}⟶2{\mathrm{Br}}^{-}\left(\mathrm{aqueous}\right); {\mathrm{E}}^{\circ }=+1.08 \mathrm{V}$

Based one the data given above, reducing power of ${\mathrm{Fe}}^{2+}, \mathrm{Al}$ and ${\mathrm{Br}}^{-}$ will increase in the order:

Consider the following $\mathrm{E}°$ values
${\mathrm{E}}_{{\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}}=0.77\mathrm{V}, \mathrm{E}{°}_{{\mathrm{Sn}}^{2+}/\mathrm{Sn}}=-0.14\mathrm{V}$

Under standard conditions, the potential for the reaction $\mathrm{Sn}\left(\mathrm{s}\right)+2{\mathrm{Fe}}^{3+}\left(\mathrm{aq}\right)⟶2{\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right)+{\mathrm{Sn}}^{2+}\left(\mathrm{aq}\right)$ is