Answer: Distortion of the octahedral geometry (elongation along z-axis due to unequal occupation of eg orbitals).
- A Distortion of the octahedral geometry (elongation along z-axis due to unequal occupation of eg orbitals)
- B No distortion, leaving the geometry as a perfectly regular octahedron in every case under typical conditions
- C A complete rearrangement of the ligands into an largely trigonal prismatic geometry instead according to standard textbooks
- D An overall increase in complex stability while the octahedral geometry stays perfectly regular in general practice
Correct answer: A. Distortion of the octahedral geometry (elongation along z-axis due to unequal occupation of eg orbitals)
Explanation: Cu<sup>2+</sup> (d<sup>9</sup>) has an unequal eg occupancy (eg: one in dz<sup>2</sup>, one in dx2-y2... or vice versa); this unequal occupation causes a tetragonal distortion (Jahn-Teller elongation along z).
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.