Predict which of the following will be coloured in aqueous solution?



The metal ions with partially or incomplete filled d-orbitals will be coloured in aqueous solution. While the metal ions having either empty or completely filled d-orbitals are colourless. The colour will be due to d-d transition of electrons. Thus, the outer electronic configuration of metal ions are

Hence, among the given ions, ${{Ti}^{3+}}$, ${{V}^{3+}}$, ${{Mn}^{2+}}$, ${{Fe}^{3+}}$ and ${{CO}^{2+}}$ will exhibit colour in aqueous solution. While ${{Cu}^{+}}$ and ${{Sc}^{3+}}$ will be colourless.