1
LOYOLA COLLEGE (AUTONOMOUS), CHENNAI 600 034
B.Sc.DEGREE EXAMINATION -CHEMISTRY
FIFTH SEMESTER APRIL 2018
CH 5513 CH 5508 FUNDAMENTALS OF SPECTROSCOPY
Date: 04-05-2018 Dept. No. Max. 100 Marks
Time: 09:00-12:00
PART A
Answer ALL questions. (10 × 2 20 marks)
1. Account for the blue colour of the sea and sky.
2. What are hot bands? Give its significance.
3. Why UV Vis spectra observed are always broad?
4. How will you predict allowed and forbidden transition using values?
5. Give the selection rules of IR and Raman Spectra.
6. Give the mutual exclusion principle..
7. Why do we use TMS as reference in NMR Spectroscopy?
8. What is chemical shift?
9. Write the possible mass spectral fragments of C2H5OH.
10. Give the principle of mass spectrometry.
PART B
Answer any EIGHT questions: × 5 40 marks)
11. Explain harmonic and anharmonic oscillations using Morse Potential energy diagram.
12. Explain the significance of base peak and metastable peak.
13. Explain Bathochromic and Hypsochromic shifts.
14. Explain the origin of Stoke and antiStoke line?
15. Draw the possible stretching and bending vibrations for linear and non-linear AB2 molecules.
16. Distinguish between absorption and emission spectra.
17. Comment on IR vibrational frequencies for free OH group and H bonded OH group.
18. Explain the factors that control the width of a NMR signal?
2
19. Distinguish cis-stilbene from its trans isomer using NMR Spectroscopy.
20. How will you simplify complex NMR signals?
21. An organic compound consisting of H and O shows the peak height ratio M M+1 100 13.4. Find the number of carbon atoms per molecule of the compound.
22. How will you determine the isotopic abundance of an element using mass spectrometry?
PART C
Answer any FOUR questions: × 10 40 marks)
23. Explain the types of electronic transitions.
Explain Lambert Beer's Law, give equation.
24. What are chromophores and auxochromes? Give an example.
The transitions are stronger than transition. Account.
25. Sketch the working principle and block diagram of IR spectrophotometer.
Explain the fundamental and Fermi resonance peaks in IR spectroscopy.
26. Explain diamagnetic anisotrophy with an example.
Discuss the principle of Raman spectroscopy.
27. What is the principle of spin -decoupling?
Predict the number of signals obtained in the NMR spectrum of acetaldehyde and propane.
28. Explain the principle, instrumentation and applications of atomic absorption spectroscopy.