Hot concentrated sulphuric acid is a moderately strong oxidizing agent. Which of the following reactions does not show oxidizing behaviour?

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 $g \ mol^{-1}: Mn = 55, Cl = 35.5$ )

Purple solution of $KMnO_4 \xrightarrow{Na_2SO_4, BaCl_2}$ Pink ppt. Select the correct statement about pink ppt.

In order to oxidize a mixture of one mole of each of $FeC_2O_4$,$Fe_2(C_2O_4)_3$,$FeSO_4$ and $Fe_2(SO_4)_3$ in acidic medium,the number of moles of $KMnO_4$ required is

Which of the following combinations does not evolve $Cl_2$ gas?

The following reaction describes the rusting of iron:
$4Fe + 3O_2 \to 4Fe^{3+} + 6O^{2-}$
Which one of the following statements is incorrect?