Write the name of the cell which is generally used in hearing aids. Write the reactions taking place at the anode and the cathode of this cell.

The cell used in hearing aids is Mercury cell. Reaction occurring at cathode and anode is
Anode: $\mathrm{Zn}\left(\mathrm{Hg}\right)+2{\mathrm{OH}}^{-}\to \mathrm{ZnO}\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}+2{\mathrm{e}}^{-}$
Cathode: $\mathrm{HgO}+{\mathrm{H}}_2\mathrm{O}+2{\mathrm{e}}^{-}\to \mathrm{Hg}\left(\mathrm{l}\right)+2{\mathrm{OH}}^{-}$