Which of the following statement in incorrect for dry cell ?

Options

A. reaction at cathode
`MnO_(2)+NH_(4)^(+)+NH_(4)^(+)+e^(-)rarrMnO(OH)+NH_(3)`
B. Manganese is redcued from +5 to +4 state
C. cell potenital is 1.5 v
D. ammonia forms complex with `Zn^(2+)` to give `Zn(NH_(2))_(4^(2+))`

Answer

B

Explanation

Anode `Zn(s) rarr Zn^(2+) (aq)+2e^(-)`
cathode `MnO_(2) + NH_(4)^(+) +e^(-) rarr MnO(OH)+NH_(3)`
At cathode manganese is reduced from +4 oxidation state to +3 oxidation state ammonia produced in reaction form with `Zn^(2+)` ions give `Zn(NH_(2))_(4^(2+))` the cell has potential of 1.5 V