Answer: Zn 2+ ([Ar]3d 10 , all paired).
- A Zn<sup>2+</sup> ([Ar]3d<sup>10</sup>, all paired)
- B Fe<sup>3+</sup> ([Ar]3d<sup>5</sup>) in typical laboratory settings
- C Cu<sup>2+</sup> ([Ar]3d<sup>9</sup>) under usual circumstances
- D Mn<sup>2+</sup> ([Ar]3d<sup>5</sup>) according to most researchers
Correct answer: A. Zn<sup>2+</sup> ([Ar]3d<sup>10</sup>, all paired)
Explanation: Zn<sup>2+</sup> has completely filled 3d<sup>10</sup> configuration with all electrons paired, making it diamagnetic.
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.