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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 · 2019 · Mains Paper I

Q9(c). Cyanide bond order

Question

Define bond order. Sketch qualitatively the MO diagram of CN⁻ ion. Further explain which of the species CN⁻, CN and CN⁺ would possess the longest bond distance.

Answer in brief

Bond order is half the difference between bonding and antibonding electron populations. CN⁺ has the lowest formal bond order, 2, and the longest expected bond.

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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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CoversCyanide bond orderMolecular orbital theory

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