In a primary dry cell, choose the incorrect statement.

Mn is oxidized from +4 to +6 oxidation state.

The correct answer is Option (1) → Mn is oxidized from +4 to +6 oxidation state.

In a primary dry cell:

Anode: Zinc container Cathode: MnO₂

Reactions: At anode → Zn is oxidized Zn → Zn²⁺ + 2e⁻

At cathode → MnO₂ is reduced Mn⁴⁺ → Mn³⁺

Ammonia formed during reaction complexes with Zn²⁺ to prevent polarization.

OPTION 1 - Mn is oxidized from +4 to +6 oxidation state.Incorrect. MnO₂ acts as a cathode depolarizer and undergoes reduction (from +4 to +3), not oxidation. There is no step where Mn goes to +6 state in a dry cell.

OPTION 2 - Zinc container acts as anode.Correct. In a primary dry cell (Leclanché cell), the zinc container is the anode where oxidation occurs: Zn → Zn²⁺ + 2e⁻

OPTION 3 - Mn is reduced from +4 to +3 oxidation state.Correct. The depolarizer is MnO₂ (+4 oxidation state for Mn). It is reduced to Mn₂O₃ or MnO(OH) where Mn is in +3 state: 2MnO₂ + 2NH₄⁺ + 2e⁻ → Mn₂O₃ + H₂O + 2NH₃ (or equivalent reaction involving Zn²⁺ and NH₃ forming complex)

OPTION 4 - Ammonia forms a complex with Zn.Correct. The NH₃ produced in the cathode reaction forms a complex with Zn²⁺: Zn²⁺ + 4NH₃ → [Zn(NH₃)₄]²⁺ This prevents accumulation of NH₃ gas and helps maintain electrolyte balance.