IGNOU MCHE 12 SOLVED ASSIGNMENT

Included:

MCHE 012 (July 2026) - ENGLISH

Tutor Marked Assignment
Spectroscopic Identification of Organic Compounds
Course Code: MCHE-012
Assignment Code: MCHE-012/TMA/2026
Maximum Marks: 100
Note: Attempt all the questions. The marks for each question are indicated against it.
1. a) How does conjugation affect the electronic transitions in organic molecules? Explain
showing its effect on absorption maxima with the help of an example.
(5)
b) Describe the effect of substituent on the UV spectra of carbonyl compounds with the
help of examples.
(5)
2. a) Differentiate between the following compounds on the basis of UV spectra. Explain
your answer.
(5)
b) Predict the expected UV and IR spectra of the following compound. (5)
3. a) Predict the max values of the following and explain your answer.
(5)
b) Explain the basis of 1H NMR spectroscopy. Which of the atomic nucleus out of 12C,
2H, 19F is not NMR active and which is NMR active? Explain you answer.
(5)
4. a) Why is TMS used as a standard in NMR spectroscopy. Explain what do upfield and
downfield signify in a NMR spectrum.
(5)
b) Explain the solvent effect in the simplication of complex spectra taking a suitable
example.
(5)
5.
Interpret the NMR spectra of the following compounds. Give the expected  values and
explain your answer.

(10)
4
6. a) Write the principle of 2D NMR. How is it different from ID NMR? (5)
b) List the benefits and limitations of COSY technqiue. (5)
7. a) Describe the use of broadband decoupling and off resonance decoupling in 13C NMR
spectroscopy.
(5)
b) Answer the following with respect to HMQC experiment.
i) its full form
ii) its role in NMR
iii) the type of nuclei involved
iv) type of spectrum obtained
(5)
8. a) Differentiate between COSY and and HETCOR experiments in 2D NMR
spectroscopy.
(5)
b) What is meant by a base peak and a molecular ion peak in mass spectrum? How is
mass spectrometry used in finding out mass of a compound? Explain.
(5)
9. a) Describe different ionisation methods involved in mass spectrometry. (5)
b) Describe the concept of cleavages taking benzylic clevages in mass spectrometry. (5)
10 a) Explain McLafferty rearrangement with the help of a suitable example. (5)
b) What kind of information is available from UV, IR, NMR and Mass spectra of an
organic compound. Explain with the help of an example. 

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