Predict which of the followingwill be coloured in aqueous solution? `Ti^(3+),V^(3+),Cu^(o+),Sc^(3+),Mn^(2+),Fe^(2+)` and `Co^(2+)` Give reasons for each.

Explanation

The ions which have incompletely filled d-orbitals will be coloured and those with fully filled or empty d-orbitals will be colourless. `Ti^(3+), V^(3+), Mn^(2+), Fe^(3+)` and `Co^(2+)` are coloured because they have incompletely filled d-orbitals. `Cu^+` and `Sc^(3+)` are colourless because `Cu^(2+)` has `3d^10 ` completely filled d-orbitals while `Sc^(3+)` has empty `(3d^0)` d-orbitals.