MHT CET202527 Apr 2025Evening ShiftChemistryd and f Block ElementsActual
Which pair of metal ions in their respective oxidation states forms colourless compounds?
Options
- AZn ²⁺ and Cu ⁺
- BCu ²⁺ and Sc ³⁺
- CTi ⁴⁺ and Mn ²⁺
- DMn ³⁺ and Ni ²⁺
Correct answer
A. Zn ²⁺ and Cu ⁺
Step-by-step solution
Which pair of metal ions forms colorless compounds? Transition metal ions exhibit color due to d-d electronic transitions, which occur only when d-orbitals are partially filled. Ions with completely empty ( d^0 ) or completely filled ( d¹⁰ ) d-subshells are typically colorless. Analysis of each pair: A) Zn ²⁺ and Cu ⁺ : Both ions have [ Ar ] 3d¹⁰ configuration ( d¹⁰ ). Since their d-orbitals are fully occupied, d-d transitions are impossible, making both ions colorless. B) Cu ²⁺ and Sc ³⁺ : Copper(II) has [ Ar ] 3d