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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 · 2023 · Paper II

Q5(e). Distinguishing ortho and para xylene

Question

Differentiate o-xylene and p-xylene using IR spectroscopy.

Answer in brief

Use the aromatic C–H out-of-plane bands: ortho disubstitution typically gives 735–770 cm⁻¹, para disubstitution about 800–860 cm⁻¹.

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Topic notes: IR spectroscopy: group frequencies, carbonyl stretching and hydrogen bonding, with every Civil Services, IFoS and Geo-Scientist PYQ →

Topic notes: ¹H and ¹³C NMR: chemical shift, spin–spin coupling and coupling constants, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversIR spectroscopyo-xylene vs p-xyleneC–H out-of-plane bendingsubstitution patternfingerprint region

All parts of Question 5