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UPSC Civil Services (Mains)

Chemistry optional

  • 2 papers
  • 250 marks each
  • 3 h per paper
  • 5 of 8 questions, Q1 and Q5 compulsory

Paper I covers physical and inorganic chemistry.

UPSC Civil Services (Mains), Chemistry optional · 2025 · Paper I

Q8(c). Lanthanides separated by change of valency

Question

How many lanthanides can be easily separated from the lanthanide mixture by using valency change method? Justify your answer.

Answer in brief

Two: cerium, through Ce⁴⁺, and europium, through Eu²⁺.

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The full model answer

As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.

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Topic notes: lanthanides and actinides (lanthanide contraction, magnetic moments, separation), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversseparation of lanthanidesvalency change methodcerium(IV)europium(II)lanthanide contractionion exchange

All parts of Question 8