Answer: Mn2+ and Fe3+.
- A Ti3+ and V3+
- B Mn2+ and Fe3+
- C Cu2+ and Zn2+
- D Cr3+ and Fe3+
Correct answer: B. Mn2+ and Fe3+
Explanation: Both Mn2+ and Fe3+ are d5, each with 5 unpaired electrons (5.92 BM), so they are isoelectronic with equal magnetic moments.
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.