Answer: 4f orbitals are well-shielded and inner; f-f transitions are Laporte-forbidden and very weak.
- A 4f orbitals are well-shielded and inner; f-f transitions are Laporte-forbidden and very weak
- B Lanthanide ions largely lack any d orbitals in their electron configuration in standard practice
- C Lanthanide ions are uniformly diamagnetic with little unpaired electrons under most conditions encountered
- D Lanthanide ions characteristically adopt unusually high oxidation states as frequently observed in practice
Correct answer: A. 4f orbitals are well-shielded and inner; f-f transitions are Laporte-forbidden and very weak
Explanation: f-f electronic transitions are both Laporte-forbidden and spin-forbidden; they give pale absorptions. Also, 4f orbitals are inner and shielded from ligand field effects.
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.