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Indian Forest Service (Mains)

Chemistry optional

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

Paper II covers organic chemistry and spectroscopy.

Indian Forest Service (Mains), Chemistry optional · 2021 · Paper II

Q5(e). Azobenzene and hydrazobenzene

Question

Explain using UV–visible spectroscopy why azobenzene is deep orange-red whereas hydrazobenzene is colourless.

Answer in brief

The azo linkage supports a conjugated chromophore with visible absorption; reduction to the hydrazo linkage interrupts that extended π system.

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Topic notes: reagents for oxidation, reduction and hydroboration, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversUV–visible spectroscopyazobenzenehydrazobenzenechromophoren–π* transition

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