VKC ScienceChemistry for written exams Telegram

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 · 2022 · Paper II

Q5(e). Isotope shift of C–H stretching

Question

A C–H stretch occurs at 2900 cm⁻¹. Calculate the approximate C–D frequency after replacing H by D.

Answer in brief

The estimated C–D stretch is about 2128 cm⁻¹, a decrease of about 772 cm⁻¹.

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 2022 solution2022 question paper

Topic notes: vibrational and electronic spectra (force constant, isotope effect, overtones, Franck–Condon), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversisotope effect in IRC–D stretching frequencyreduced massharmonic oscillatordeuteration

All parts of Question 5