N A L A N D A O P E N U N I V E R S I T Y
M.Sc. Chemistry, Part-II
PAPER-IX
(Spectroscopy)
Annual Examination, 2018
Time 3 Hours. Full Marks 80
Answer any FIVE Questions. All questions carry equal marks.
1. Which of the following nuclei do not show nuclear magnetic resonance
1H 2H 12C 14N 16O 13C and 19F .
NMR spectra are not observed in 12C nuclei, because it nuclear spin quantum number
I
2
1 I 0 I 1 I -1.
The number of modes of bonding vibration in non-lineer molecule containing n atoms is
2n 5 3n 5 2n 6 3n 6
The lines in a pure rotational spectrum, are not exactly equally-spaced because of the
Decrease in bond-length Large increase in bond-length
Centrifugal distortion None of them
In a rotational-vibrational spectra, R-branch corresponds to transition:
0 1 Nome of them
2. Write notes on any two of the following
Selection rules for pure rotational Roman spectra of a diatomic molecules
Coupling constant
Pascal triangle
3. Express and explain the zero-point energy. Are you agree with the concept of zero-point
energy Explain it.
4. Notes on any two of the following
Franck-Condon Principles McLaffery rearrangement Beer-Lamberts law
5. Describe the basic principle of mass spectrometry. Write notes on
Molecular ionpeak Metastable peaks
6. Explain any two of the following
d-d transition 6 *transition Franck-condon principle
7. Answer the following
Coupling constant
An atom shows or gives rise to line spectra while molecules show band spectra.
8. Woodward-Fieser Rules for conjugated dienes, write and explain.
9. Why TMS (Tetramethylsilane) is used as a reference compound in NMR spectroscopy.
For the detection of aldehydes and ketones, which transition is more authentic
*on n give the answer with reason.
Which of the following diatonic molecules do not absorb in the infra-red region
Hcl, ClBr, N2, H2, O2
Which of the following are microwave active
Hcl Co2 H2 O2
10. Explain the Zero-field splitting in ESR Spectroscopy.