In a weak alkaline medium,iodide is changed into which of the following compounds by $KMnO_4$?

Balance the following redox reactions by the ion-electron method:
$(a)$ $MnO_4^-(aq) + I^{-}(aq) \rightarrow MnO_2(s) + I_2(s)$ (in basic medium)
$(b)$ $MnO_4^-(aq) + SO_2(g) \rightarrow Mn^{2+}(aq) + HSO_4^-(aq)$ (in acidic solution)
$(c)$ $H_2O_2(aq) + Fe^{2+}(aq) \rightarrow Fe^{3+}(aq) + H_2O(l)$ (in acidic solution)
$(d)$ $Cr_2O_7^{2-} + SO_2(g) \rightarrow Cr^{3+}(aq) + SO_4^{2-}(aq)$ (in acidic solution)

Assign $A, B, C, D$ from the given type of reaction.
$Cr_2O_7^{2-} + H^{+} + SO_3^{2-} \longrightarrow Cr^{3+}(aq.) + SO_4^{2-}$

Consider the following reaction occurring in basic medium $2MnO_4^- (aq) + Br^- (aq) \to 2MnO_2 (s) + BrO_3^- (aq)$. How can the above reaction be balanced further?

For the balanced redox reaction $aZn + b \, HNO_3 \to c \, Zn(NO_3)_2 + d \, NH_4NO_3 + 3H_2O$,the value of $b$ is:

In neutral or alkaline solution,$MnO_{4}^{-}$ oxidises thiosulphate to.