Conventional methods cannot be used for separation of individual lanthanoid elements beacause their properties are quite similar. Suggest a suitable method for their separation.

Explanation

Ion exchange method can be used to separate individual lanthanoid elements. The method is based upon the fact that hydrated radii of lanthanoid ions increase with increasing atomic numbers. Thus, when a solution containing a mixture of several lanthanoid ions is passed through a column of a cation exchange resin, the heavier elements will come out first from the coulumn.