Answer: 3MnO42- + 4H+ → 2MnO4- + MnO2 + 2H2O (Mn goes from +6 to +7 and +4).
- A 3MnO42- + 4H+ → 2MnO4- + MnO2 + 2H2O (Mn goes from +6 to +7 and +4)
- B Manganese remains largely in the +6 oxidation state throughout
- C Manganese is largely reduced down to the +2 oxidation state during normal conditions
- D No reaction occurs when MnO42- is acidified as generally observed
Correct answer: A. 3MnO42- + 4H+ → 2MnO4- + MnO2 + 2H2O (Mn goes from +6 to +7 and +4)
Explanation: Manganate (Mn +6) is unstable in acid and disproportionates to permanganate (Mn +7) and MnO2 (Mn +4).
Aqueous solutions of transition metal ions show characteristic colours caused by electrons absorbing visible light to jump between split d-orbitals; the exact colour depends on the metal, its oxidation state, and surrounding ligands.
Concept context
Transition metals (d-block) and lanthanides/actinides (f-block). Known for coloured compounds, variable oxidation states, complex formation, and catalytic properties. Frequently tested in JEE and NEET.