VKC ScienceChemistry for written exams Telegram

UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2025 · Mains Paper III

Q7(c)(ii). Norrish Type II against Type I in two ketones

Question

Which of the following two ketones X and Y will be more prone to Norrish Type II reaction? Give plausible mechanism and justify your answer about the reactivity of X and Y. [structures of X and Y given in the paper]

Answer in brief

X (hexan-2-one) is more prone to Norrish Type II: it gives acetone and propene. In Y the faster process is α-cleavage (Type I).

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 2025 solution2025 question paper

Topic notes: organic photochemistry and Norrish reactions, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversNorrish Type IINorrish Type Iphotochemistry of ketonesgamma hydrogen abstraction1,4-biradical

All parts of Question 7