2MnO_ 2(s) + 2NH_4^+ + 2e^- arrow Mn_2O_ 3(s) + 2NH_ 3(aq) + H_2O_...

The given reaction is the reduction half-reaction that takes place at the cathode in a Leclanche cell (also known as a dry cell).

At the cathode, manganese dioxide is reduced in the presence of ammonium ions to form manganese(III) oxide (or MnO(OH)), ammonia, and water.

The overall cathode reaction is:
$2\text{MnO}_{2(s)} + 2\text{NH}_4^+ + 2e^- \rightarrow \text{Mn}_2\text{O}_{3(s)} + 2\text{NH}_{3(aq)} + \text{H}_2\text{O}_{(l)}$

Thus, the cell that exhibits this net reduction reaction is the Leclanche cell.

Answer: Leclanche cell