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UPSC Combined Geo-Scientist

Chemist

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

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2017 · Mains Paper III

Q6(b). Benzene and cyclooctatetraene orbitals

Question

Draw the π-MO energy diagrams for benzene and cyclooctatetraene (COT).

Answer in brief

Benzene has a closed-shell six-electron aromatic configuration. Planar regular COT would have two singly occupied nonbonding orbitals; actual COT distorts to a nonaromatic tub.

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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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CoversBenzenecyclooctatetraene orbitalsAromaticity and molecular orbitals

All parts of Question 6