Indian Forest Service (Mains), Chemistry optional · 2023 · Paper II

Q8(b). A C9H12 alkylbenzene mass spectrum

5 marks
Topic: Principles of spectroscopy and applications in structure elucidation
Question only

Question

For C₉H₁₂ with m/z 120, 92, 91, 77, 51, propose a structure and explain the ion at 92.

Model answer

The free solution for 2023 answers questions 1, 2, 5, 6 and 7, the ones picked in its time plan. This part is not answered on the site yet. New answers are announced on Telegram.

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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 spectrometryMcLafferty rearrangementpropylbenzenetropylium ionm/z 92

All parts of Question 8

8(a) Selective epoxidation and carbonyl rearrangement10 marks
8(b) A C9H12 alkylbenzene mass spectrum5 marks
8(c) Benzene radical anion5 marks
8(d) Average repeat-unit mass of a terpolymer5 marks
8(e) Identification of glutaric anhydride15 marks