Which of the following metal ions is colored in aqueous solution ?

Options

A. `Sc^(3+)`
B. `Ti^(4+)`
C. `Zn^(2+)`
D. `V^(4+)`

Answer

D

Explanation

When an electron from a lower energy d orbital is excited to a higher energy d orbital the tnergy of excitation corresponds to the frequency of light absorbed. This frequency for d-d transition generally lies in the visible region. The d-d transtion is not possible in `Sc^(3+)` and `Ti^(4+)` as they have `d^(0)` configuration. Similarly, d-d transition is not possible in `Zn^(2+)` as it as `d^(10)` configuration. The `V^(4+)` ion `(sd^(1))` is capable of executing d-d transition. In aqueous solution, where `H_(2)O` molecules are ligands, the `V^(4+)` ion is blue in color.