In which of the following reactions does the oxidation number not change?

Which is not the true statement about $KMnO_4$?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Pb(CH_3COO)_2 + Na_2CrO_4 \longrightarrow PbCrO_4 \downarrow + 2CH_3COONa$

To measure the quantity of $MnCl_2$ dissolved in an aqueous solution,it was completely converted to $KMnO_4$ using the reaction,
$MnCl_2 + K_2S_2O_8 + H_2O \longrightarrow KMnO_4 + H_2SO_4 + HCl$ (equation not balanced).
Few drops of concentrated $HCl$ were added to this solution and gently warmed. Further,oxalic acid $(225 \ mg)$ was added in portions till the colour of the permanganate ion disappeared. The quantity of $MnCl_2$ (in $mg$) present in the initial solution is . . . . . . . . . (Atomic weights in $g \ mol^{-1}: Mn = 55, Cl = 35.5$ )

In order to oxidize a mixture of $1 \text{ mole}$ each of $FeC_2O_4$, $Fe_2(C_2O_4)_3$, $FeSO_4$, and $Fe_2(SO_4)_3$ in an acidic medium, the number of moles of $KMnO_4$ required is:

For the reaction $SO_2 + 2H_2S \to 3S + 2H_2O$,which option represents twice the equivalent weight of the oxidizing agent?