Regarding batteries, some reactions are given below. The false combination is

• A

  ${\mathrm{MnO}}_2+{\mathrm{NH}}_4^{+}+{\mathrm{e}}^{-}\to \mathrm{MnO}\left(\mathrm{OH}\right)+{\mathrm{NH}}_3 . . . \mathrm{Cathodic} \mathrm{reaction} \mathrm{in} \mathrm{dry} \mathrm{cell}$

• B

  $\mathrm{Zn}-\mathrm{Hg}+2{\mathrm{OH}}^{-}\to \mathrm{ZnO}+{\mathrm{H}}_2\mathrm{O}+\mathrm{Hg}+2{\mathrm{e}}^{-} . . . \mathrm{Anodic} \mathrm{reaction} \mathrm{in} \mathrm{mercury} \mathrm{cell}$

• C

  $\mathrm{Pb}+{\mathrm{SO}}_4^{-2}\to {\mathrm{PbSO}}_4+2{\mathrm{e}}^{-} . . . \mathrm{Anodic} \mathrm{reaction} \mathrm{in} \mathrm{lead} \mathrm{storage} \mathrm{battery} \mathrm{during} \mathrm{dischage}$

• D

  $2{\mathrm{H}}_2\mathrm{O}+2{\mathrm{e}}^{-}\to {\mathrm{H}}_2+4{\mathrm{OH}}^{-} . . . \mathrm{Cathodic} \mathrm{reaction} \mathrm{in} {\mathrm{H}}_2-{\mathrm{O}}_2 \mathrm{fuel} \mathrm{cell}$