Which of the following prediction is correct when the transition metal ion is colourless?

Step-by-step solution

The colour of transition metal ions is primarily due to d-d transitions, which require the presence of partially filled d-orbitals. When the d-orbitals are completely empty ( d^0 configuration, e.g., Sc³⁺ , Ti⁴⁺ ) or completely filled ( d¹⁰ configuration, e.g., Zn²⁺ , Cu^+ ), d-d transitions are not possible. In both d^0 and d¹⁰ configurations, there are no unpaired electrons. Therefore, a transition metal ion is colourless when it contains 0 unpaired electrons. Answer: it contains 0 unpaired electrons