The number of moles of $KMnO_4$ reduced by one mole of $KI$ in alkaline medium is

Assuming complete ionisation,same moles of which of the following compounds will require the least amount of acidified $KMnO_4$ for complete oxidation?

$2 MnO_4^{-} + bI^{-} + cH_2O \rightarrow xI_2 + yMnO_2 + zOH^{-}$
If the above equation is balanced with integer coefficients,the value of $z$ is . . . . . .

In the following balanced chemical reaction,$IO_3^- + aI^- + bH^+ \to cH_2O + dI_2$,what are the values of $a, b, c$ and $d$ respectively?

Identify the elements undergoing reduction and oxidation respectively in the following redox reaction.
$3 H_3AsO_{3(aq)} + BrO_{3(aq)}^{-} \rightarrow Br_{(aq)}^{-} + 3 H_3AsO_{4(aq)}$

For the redox reaction $MnO_4^- + C_2O_4^{2-} + H^{+} \to Mn^{2+} + CO_2 + H_2O$,the correct coefficients of the reactants for the balanced reaction are:
$MnO_4^-$ : $C_2O_4^{2-}$ : $H^{+}$