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 · 2016 · Paper II

Q5(e). Chemical shift at 60 MHz and 100 MHz

Question

A compound contains two types of protons which exhibit signals at 139·2 Hz and 430·2 Hz downfield from TMS in a spectrometer operating at 60 MHz. What will be their relative position when measured on a 100 MHz instrument ?

Answer in brief

At 100 MHz: 232 Hz and 717 Hz from TMS (separation 485 Hz in place of 291 Hz); δ = 2.32 and 7.17 ppm unchanged.

With any Mains test series

Read the key points and the full model answer with a Mains test series

Every Mains test series (Civil Services, IFoS or Geo-Scientist) opens the solved IFoS Mains PYQ answers, the notes, the handbook and the daily answer archive until your Mains. The first test of each series is free. Civil Services and Geo-Scientist Mains PYQ solutions and Geo-Scientist Prelims PYQ solutions are free for everyone.

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 any Mains test series.
Read the whole 2016 solution2016 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 →

Coverschemical shiftindependent of the field

All parts of Question 5