Predict which of the following will be coloured in aqueous solution ?
`Ti^(3+), V^(3+),Cu^(+),Sc^(3+), Mn^(2+), Fe^(3+), Co^(2+)`.

Explanation

Only those ions will be coloured which have incomplete d-orbitals. The ions with either empty or filled d-orbitals are colourless. Keeping this in view , the coloured ions among the given list are :
`Ti^(3+)(3d^(1)), V^(3+)(3d^(2)), Mn^(2+)(3d^(5)), Fe^(3+)(3d^(5)), Co^(2+)(3d^(7))`
`Sc^(3+)(3d^(@))` and `Cu^(+)(3d^(10))` ions are colourless.