Which statement about transition metals and their complexes is correct?
Scandium is classified as a transition metal because it is located in the d-block of the Periodic Table.
The copper(I) ion, Cu+\text{Cu}^+Cu+, forms coloured aqueous complexes because it has a partially filled d sub-shell.
When a coordinate bond is formed in a complex ion, the ligand acts as a Lewis base by donating a lone pair of electrons to the central metal ion.
The coordination number of the complex ion [Cr(C2O4)3]3−[\text{Cr}(\text{C}_2\text{O}_4)_3]^{3-}[Cr(C2O4)3]3− is 3 because there are three ethanedioate ligands.
