In the dry cell or Leclanche cell, a carbon rod serves as the cathode, which is immersed in the electrolyte in the center of the cell. At cathode, manganese is reduced from the `"_______"` oxidation state to the `"_______"` state.

Options

A. `+7, +5`
B. `+7, +4`
C. `+4, +1`
D. `+4, +3`

Answer

D

Explanation

The electrode reactions are complicated but are approsmimately these:
`{:("Anode :" Zn(s)rarrZn^(2+)(aq.)+2e^(-)),("Cathode :" 2NH_(4)^(+)(aq.)+2MnO_(2)(s)+2e^(-)rarrMn_(2)O_(3)(s)+H_(2)O(l)+2NH_(3)(aq.)):}/("Overall :" Zn(s)+2NH_(4)^(+)(aq.)2MnO_(2)(s)rarrZn^(2+)(aq.)+2NH_(3)(aq.)+H_(2)O(l)+Mn_(2)O_(3)(s))`
In `MnO_(2)`, the oxidation state of `Mn` is `+4` while in `Mn_(2)O_(3)` the oxidation state of `Mn` of `+3`.