Indian Forest Service (Mains), Chemistry optional · 2024 · Paper I
Q7(c). Divalent europium and samarium
Question
Explain why the 2+ oxidation state is stabilised in Eu (atomic number 63). Among Ce (58), Tb (65) and Sm (62), which is most likely to show the 2+ state?
Model answer
The free solution for 2024 answers questions 1, 2, 4, 5 and 8, the ones picked in its time plan. Question 7 is answered in full in the IFoS Chemistry Paper I, 2021 to 2025 book, with every part of every paper.
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UPSC Indian Forest Service (Main) Chemistry Paper I: Model Answers 2021 to 2025
- All eight questions of each paper, with the question printed above its answer
- Physical chemistry numericals worked with units; inorganic structures drawn
- Topic-wise weightage and a topic-wise index
Coverseuropium(II)lanthanide oxidation stateshalf-filled 4f7samarium(II)f-block chemistry
All parts of Question 7
- 7(a) Why CO and N₂ differ as ligands15 marks
- 7(b)(i) Hydrogen addition to Vaska complex5 marks
- 7(b)(ii) Fluxionality of tetracyclopentadienyltitanium10 marks
- 7(c) Divalent europium and samarium10 marks