Select the number of reagent/treatment which can convert ${\mathrm{Br}}_{\mathrm{Aq}}^{-}$ to ${\mathrm{Br}}_2$:-

conc. ${\mathrm{H}}_3{\mathrm{PO}}_4$, conc. ${\text{H}}_2{\mathrm{SO}}_4$, conc. ${\mathrm{HNO}}_3$, $\mathrm{Pb}({\mathrm{CH}}_3\mathrm{COO}{)}_2$, Chlorine water, ${\mathrm{I}}_2$ crystals, ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7/{\mathrm{H}}^{+}$, ${\mathrm{KMnO}}_4/{\mathrm{H}}^{+}$, Δ with ${\mathrm{PbO}}_2/{\mathrm{H}}^{+}$

The redox reaction among the following is:

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