Answer: Mn 2+.
- A Mn<sup>2+</sup>
- B Mn<sup>3+</sup>
- C MnO<sub>4</sub><sup>-</sup>
- D MnO<sub>4</sub><sup>2-</sup>
Correct answer: A. Mn<sup>2+</sup>
Explanation: Mn<sup>2+</sup> ([Ar]3d<sup>5</sup>) is the most stable oxidation state in acidic conditions due to the extra stability of the half-filled d<sup>5</sup> configuration.
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.