Answer: Complex with large crystal field splitting (strong field ligands).
- A Complex with large crystal field splitting (strong field ligands)
- B A complex showing only a small crystal field splitting energy
- C Any diamagnetic complex regardless of its splitting energy
- D A complex with an empty d<sup>0</sup> configuration and no d electrons to excite
Correct answer: A. Complex with large crystal field splitting (strong field ligands)
Explanation: Stronger field ligands cause larger splitting (Delta), allowing d-d transitions of higher energy, giving more intense (and often deeper) colour.
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.