$KMnO_4$ in basic medium is reduced to

In the chemical reaction between stoichiometric quantities of $KMnO_4$ and $KI$ in a weakly basic or neutral solution,what is the number of moles of $I_2$ released for $4$ moles of $KMnO_4$ consumed?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$CuSO_4 + Zn_{(s)} \longrightarrow ZnSO_4 + Cu$

Consider the following redox reaction taking place in acidic medium: $BH_{4}^{-}(aq) + ClO_{3}^{-}(aq) \rightarrow H_{2}BO_{3}^{-}(aq) + Cl^{-}(aq)$. If the Nernst equation for the above balanced reaction is $E_{cell} = E_{cell}^{o} - \frac{RT}{nF} \ln Q$, then the value of $n$ is . . . . . . . (Nearest integer)

Given the redox reaction:
$X Na_2HAsO_3 + Y NaBrO_3 + Z HCl \longrightarrow NaBr + H_3AsO_4 + NaCl$
The values of $X$,$Y$,and $Z$ in the balanced equation are respectively:

The number of moles of acidified $KMnO_4$ required to convert one mole of sulphite ion into sulphate ion is