Potassium permanganate is prepared from the mineral pyrolusite, `MnO_(2)`. Its crystals have deep purple colour. It acts as an oxidizing agent in the neutral, alkaline as well as acidic medium. In acidic medium , it is used in volumetric analysis for estimation of ferrous salts, oxalates etc. The titrations are carried out in presence of `H_(2)SO_(4)`. However ,before using itas a titrant, it is first standized with standard oxalic acid solution or Mohr salt solution. In one of the experiments on titration , 13.4 g of dry pure sodium oxalate ( molar mass `=134 g mol^(-1)` ) was dissolved in 100mLof distilled water and then 100 mL of 2M `H_(2)SO_(4)` were added. The solution, was cooled to `25.30^(@) C`. Now to this solution , 0.1 M `KMnO_(4)` solution was added till a very faint pink colour persisted. The purple colour of `KMnO_(4) ` is due toA. incomplete d-subhsellB. ionic nature of `KMnO_(4)`C. ionic nature of `KMnO_(4)`D. resonance in `MnO_(4)^(-)`ion