Match the following columns. 

	Column I		Column II
A.	${\mathrm{Fe}}^{3+}\text{ and }{\mathrm{I}}^{-}$	p.	${\mathrm{E}}_{\mathrm{cell}}^{\circ }=+\mathrm{ve}$
B.	${\mathrm{Fe}}^{3+} \mathrm{and} {\mathrm{Br}}^{-}$	q.	${\mathrm{\Delta G}}^{\circ }=+ \mathrm{ve}$
C.	$\mathrm{Zn}\text{ and }{\mathrm{H}}^{+}$	r.	${\mathrm{E}}_{\text{cell }}^{\circ }=-{\mathrm{E}}_{\text{electrode }}^{\circ }$
D.	$\mathrm{Br} \mathrm{and} {\mathrm{Fe}}^{2+}$	s.	${\mathrm{\Delta G}}^{\circ }=-\mathrm{ve}$

$\left[\text{ Given, }{\mathrm{E}}_{{\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}}^{\circ }=0.77,{\mathrm{E}}_{\left[\frac{1}{2}{\mathrm{I}}_2/1^{-}\right]}^{\circ }=+0.54\right.$
$\left.{\mathrm{E}}_{1/2{\mathrm{Br}}_2/{\mathrm{Br}}^{-}}=1.09,{\mathrm{E}}_{{\mathrm{Zn}}^{2+}/\mathrm{Zn}}^{{\circ }^{\circ }}=-0.76\right]$

$\mathrm{A}\to \mathrm{p},\mathrm{s};\mathrm{B}\to \mathrm{q};\mathrm{C}\to \mathrm{p},\mathrm{r},\mathrm{s};\mathrm{D}\to \mathrm{p},\mathrm{s}$
A reaction is feasible, if its ${\mathrm{E}}_{\mathrm{cell}}^{\mathrm{o}}$ value is positive.
A. ${\mathrm{Fe}}^{3+}\left(\mathrm{aq}\right)+{\mathrm{I}}^{-}\left(\mathrm{aq}\right)⟶{\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right)+\frac{1}{2}{\mathrm{I}}_2\left(\mathrm{g}\right)$
    ${\mathrm{E}}_{\text{cell }}^{\circ }={\mathrm{E}}_{\left({\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}\right)}-{{\mathrm{E}}^{\circ }}_{1/2}{\mathrm{I}}_{2/1^{-}}=(0.77-0.54)=0.23$
     The reaction is feasible.
    $\text{ i.e. }{\mathrm{\Delta G}}^{\circ }=-\mathrm{ve}$
B. ${\mathrm{Fe}}^{3+}\left(\mathrm{aq}\right)+{\mathrm{Br}}^{-}\left(\mathrm{aq}\right)⟶{\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right)+\frac{1}{2}{\mathrm{Br}}_2\left(\mathrm{g}\right)$
    ${\mathrm{E}}_{\text{cell }}^{\circ }={\mathrm{E}}_{\left({\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}\right)}^{\circ }-{{\mathrm{E}}^{\circ }}_{1/2{\mathrm{Br}}_2/{\mathrm{Br}}^{-}}=0.77-1.09=-0.32\mathrm{V}$
   The reaction is not feasible.
    $\text{ i.e. }{\mathrm{\Delta G}}^{\circ }=+\mathrm{ve}$
C.$\frac{1}{2}{\mathrm{Br}}_2\left(\mathrm{aq}\right)+{\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right)⟶{\mathrm{Br}}^{-}\left(\mathrm{aq}\right)+{\mathrm{Fe}}^{3+}\left(\mathrm{aq}\right)$
     ${\mathrm{E}}_{\text{cell }}^{\circ }={\mathrm{E}}_{\left(1/2{\mathrm{Br}}_2/{\mathrm{Br}}^{-}\right)}^{\circ }-{\mathrm{E}}_{\left({\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}\right)}=1.09-0.77=0.32\mathrm{V}$
    The reaction is feasible.
    ${\mathrm{\Delta G}}^{\circ }=-\mathrm{ve}$