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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper I covers inorganic chemistry.

UPSC Combined Geo-Scientist, Mains · 2021 · Mains Paper I

Q2(a). ReO₃ unit cell and perovskite relation

Question

Sketch the unit cell of ReO₃ and determine (i) the coordination number of Re and O, and (ii) the identity of the structure type that would be generated if a cation is inserted in the centre of each ReO₃ unit cell.

Answer in brief

Re has coordination number 6 and O has 2. Filling the body-centred cavity generates the perovskite structure type.

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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: inorganic solids: perovskite, spinel, ReO₃, corundum, high-Tc superconductors and solid-state synthesis, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversReO3 structureperovskiteunit cellcoordination numbercorner-sharing octahedra

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