Identify the pair of transition metal ions in which both ions are colourless in aqueous solution and possess a d¹⁰ electronic configuration.

Step-by-step solution

The colour of transition metal ions in aqueous solutions is primarily due to d-d transitions, which require the presence of unpaired d -electrons. Ions with d⁰ or d¹⁰ configurations do not undergo d-d transitions and are therefore colourless. Let us evaluate the electronic configurations of the given ions: Sc ³⁺ : [ Ar ] 3d⁰ (colourless, but has a d⁰ configuration) Ti ⁴⁺ : [ Ar ] 3d⁰ (colourless, but has a d⁰ configuration) Cu ⁺ : [ Ar ] 3d¹⁰ (colourless, has a d¹⁰ configuration) Zn ²⁺ : [ Ar ] 3d¹⁰ (colourless, ha