Q. Show the Colour of actinides and lanthanides Ions?

Ions of actinides and lanthanides are coloured in the solid state as well as in aqueous solution, as is the case with the ions of transition metals. You have studied in the preceding unit that the colours of transition metal ions arise as of absorption of light due lo d - d electronic transitions. As there are no electrons in the d-orbitals, the colours of lanthanide and actinide ions arise due to electronic transitions in the 4f and Sf orbitals.  Colours of hydrated lanthanide and actinide ions are shown in Table, respectively.