Step 1:

Preparation of potassium permanganate is as follows:

Potassium permanganate is prepared by fusion of MnO₂ with an alkali metal hydroxide and an oxidizing agent like KNO₃ . This produces the dark green K₂MnO₄ which disproportionates in a neutral or acidic solution to give permanganate. 

The reactions are as follows:

2MnO₂ + 4KOH + O₂ → 2K₂MnO₄ + 2H₂O 
3MnO₄^2– + 4H⁺ → 2MnO₄^– + MnO₂ + 2H₂O

Step 2:

The reaction of acidified permanganate solution with (i) iron(II) ions (ii) SO₂ and (iii) oxalic acid are as follows:

(i) Fe²⁺ ion (green) is converted to Fe³⁺ (yellow) when acidified permanganate solution reacts with Fe²⁺. The reaction is as follows:

5Fe²⁺ + MnO₄^– + 8H⁺ → Mn²⁺ + 4H₂O + 5Fe³⁺ 

(ii) The reaction between SO₂ and acidified permanganate solution is as follows:

\(\begin{aligned} 2 \mathrm{MnO}_{4}^{-}+2 \mathrm{H}_{2} \mathrm{O} +5 \mathrm{SO}_{2} \rightarrow \mathrm{SO}_{4}^{2-} +2 \mathrm{Mn}^{2+} &+2 \mathrm{H}_{2} \mathrm{SO}_{4} \end{aligned}\)

(iii) Acidified permanganate solution oxidizes oxalates to carbon dioxide. The reaction is as follows:

\(2 \mathrm{MnO}_{4}^{-}+16 \mathrm{H}^{+}+5 \mathrm{C}_{2} \mathrm{O}_{4}^{2-} \rightarrow 2 \mathrm{Mn}^{2+}+8 \mathrm{H}_{2} \mathrm{O}+10 \mathrm{CO}_{2}\)