In the following equation ${\mathrm{MnO}}_2$ acts as 

${{\mathrm{MnO}}_4}^{-2}+2{\mathrm{H}}_2\mathrm{O}+2{\mathrm{e}}^{-}\to {\mathrm{MnO}}_2+4{\mathrm{OH}}^{-}$

The redox reaction among the following is:

Which is reduced in the following reaction

$\left(\mathrm{a}\right)2\mathrm{KI}\left(\mathrm{aq}\right)+\left(\mathrm{b}\right){\mathrm{Cl}}_2\left(\mathrm{aq}\right)\to 2\mathrm{KCl}+{\mathrm{I}}_2\left(\mathrm{aq}\right)$

Strongest reducing agent among the following is

(i) ${\mathrm{Na}}^{+}+{\mathrm{e}}^{-}\to {\mathrm{Na}}_{\left(\mathrm{S}\right)}-2.7{\mathrm{E}}^{\mathrm{\Theta }}/\mathrm{v}$

(ii) ${\mathrm{Al}}^{3+}+3{\mathrm{e}}^{-}\to {\mathrm{Al}}_{\left(\mathrm{S}\right)}-1.66{\mathrm{E}}^{\mathrm{\theta }}/\mathrm{v}$

(iii) ${\mathrm{F}}_{2\left(\mathrm{g}\right)}+2^{\mathrm{e}-}\to 2 {\mathrm{F}}^{-}+2.87{\mathrm{E}}^{\mathrm{O}}/\mathrm{v}$

(iv) $2{\mathrm{H}}_2\mathrm{O}+2{\mathrm{e}}^{-}\to {\mathrm{F}}_{2\left(\mathrm{g}\right)}+2{\mathrm{OH}}^{-}{}_{\left(9\mathrm{g}\right)}-0.83{\mathrm{E}}^{\mathrm{\Theta }}/\mathrm{v}$

In the following resonance structures, the curved arrow indicates that electrons are shifted from