Which of the following is a redox reaction?

The total change in the oxidation state of manganese involved in the reaction of $KMnO_4$ and potassium iodide in the acidic medium is $..........$.

In the reaction between $KI$ and acidic potassium dichromate solution,the oxidation state of chromium in the final product is ........

For the redox reaction
$MnO_{4}^{-} + C_{2}O_{4}^{2-} + H^{+} \longrightarrow Mn^{2+} + CO_{2} + H_{2}O$
the correct coefficients of the reactants for the balanced equation are
$MnO_{4}^{-} \quad C_{2}O_{4}^{2-} \quad H^{+}$

In the equation $H_2S + 2HNO_3 \to 2H_2O + 2NO_2 + S$,the equivalent weight of hydrogen sulphide is:

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