Which of the following reagents causes the aqueous colored solution of acidic $KMnO_4$ to become colorless?

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:
$MnO_4^-$ : $C_2O_4^{2-}$ : $H^{+}$

Assign $A, B, C, D$ from the given type of reaction.
$CuSO_4 + 2KCN \longrightarrow CuCN \downarrow + (CN)_2 \uparrow + K_2SO_4$

Equivalent mass of the oxidizing agent in the reaction $SO_2 + 2H_2S \to 3S + 2H_2O$ is

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Cl_{2(g)} + 2KI(aq.) \longrightarrow 2KCl(aq.) + I_2(s)$

For the reaction $3K_2MnO_4 + 2H_2SO_4 \rightarrow 2KMnO_4 + K_2SO_4 + MnO_2 + 2H_2O$,what is the stoichiometric ratio of the reactants $K_2MnO_4$ to $H_2SO_4$?