UPSC Civil Services (Mains), Chemistry optional · 2023 · Paper II
Q8(a)(ii). Ketone C₇H₁₂O with λmax = 249 nm
Question
Draw the structural formula of a ketone with molecular formula C₇H₁₂O that absorbs in the UV with λmax = 249 nm.
Answer in brief
3,4-Dimethylpent-3-en-2-one, CH₃CO–C(CH₃)=C(CH₃)₂.
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.
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.
How to plan and write this answer: book source, keyword map and model answer →
CoversWoodward–Fieser rulesα,β-unsaturated ketoneUV spectroscopyλmaxenone
All parts of Question 8
- 8(a)(i) Doxepin: site of ionisation, m/z 58 ion and metastable ion10 marks
- 8(a)(ii) Ketone C₇H₁₂O with λmax = 249 nm5 marks
- 8(b)(i) Microwave activity; rotational constants of CO10 marks
- 8(b)(ii) Expected J(Ha–Hb) in three alkenes5 marks
- 8(c)(i) Keto and enol percentages of acetylacetone from integration10 marks
- 8(c)(ii) Two isomeric amides C₅H₁₁NO by mass spectrometry5 marks
- 8(c)(iii) Fundamental vibrations of CO₂ and their IR activity5 marks