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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 · 2024 · Paper II

Q8(a)(ii). IR-active vibrations

Question

Which of CH₃OH, CH₃NH₂, CO₂, CH₄ and CO are infrared active?

Answer in brief

All five possess IR-active vibrational modes. A permanent molecular dipole is not required.

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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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Topic notes: vibrational and electronic spectra (force constant, isotope effect, overtones, Franck–Condon), with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversIR selection ruleIR active vibrationschange in dipole momentCO2 normal modesmethane IR

All parts of Question 8