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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 · 2025 · Paper II

Q5(e). Mass fragmentation of acetic anhydride

Question

Assign m/z 102, 60, 43, 42, 15 for C₄H₆O₃ and identify the base peak.

Answer in brief

The expected compound is acetic anhydride, (CH₃CO)₂O; the characteristic base peak is the acetyl ion at m/z 43.

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Topic notes: mass spectrometry: molecular ion, metastable peak and McLafferty rearrangement, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversmass spectrometry fragmentationacetic anhydrideacylium ion m/z 43base peakketene loss

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