VKC ScienceChemistry for written exams Telegram

UPSC Civil Services (Mains)

Chemistry optional

  • 2 papers
  • 250 marks each
  • 3 h per paper
  • 5 of 8 questions, Q1 and Q5 compulsory

Paper II covers organic chemistry and spectroscopy.

UPSC Civil Services (Mains), Chemistry optional · 2021 · Paper II

Q8(b)(i). C₉H₁₈O with a single ¹H NMR line

Question

A molecule with molecular formula C₉H₁₈O exhibits only one signal at δ 1.2 ppm in its ¹H NMR spectrum. It also exhibits a strong absorption at 1710 cm⁻¹ in its IR spectrum. Propose a structure for this molecule.

Answer in brief

Di-tert-butyl ketone, 2,2,4,4-tetramethylpentan-3-one, (CH₃)₃C–CO–C(CH₃)₃.

Part of VKC Basic

Read the key points and the full model answer with VKC Basic

VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.

See what is included Already a member? Sign in

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.

The handwritten model answer pages open with the VKC plan.
Read the whole 2021 solution2021 question paper

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

Coversstructure from NMRdi-tert-butyl ketonedouble bond equivalentC9H18OIR 1710 ketone

All parts of Question 8