B.Sc. III (Semester (Entrepreneurship) (CGPA) Examination, 2018
industrial chemistry
Spectroscopic Methods
Day and Date Tuesday, 17-4-2018 Max. Marks 70
Time 2.30 p.m. to 5.00 p.m.
Instructions All questions are compulsory.
Figures to the right indicate full marks.
Draw neat labelled diagram.
1. Select most correct alternative among the following and rewrite the following 14
IR spectroscopy is mainly useful in the determination of
Conjugation Functional group
Molecular weight Atomic weight
ii) An example of Auxochrome is
C ≡ C
-NH2 All these
iii) In mass spectroscopy, the intensity assigned to base peak is
50% 90% 100%
iv) When a halogen atom is attached to methyl group, then the δ values
decreases with electronegativity of halogen atom
not affected by electronegativity
increases wirh electronegativity
negligible
The finger print region of the IR spectrum lies in the range
1350 650 cm-1 4000 1350 cm-1
4000 650 cm-1 650 50 cm-1
vi) The transition energy for is than n→π∗ transition.
less equal half greater
vii) Molecular ions peak is not generally visible in case of
halides alcohols
aldehydes ketones
viii) Among the following which is magnetic nuclei
1H1 6C12 1H2 7N14
ix) is an example of homocyclic diene.




Mass spectroscopy is a technique.
high pressure low temperature
low pressure high temperature
xi) The proton is charged spinning nuclei with a nuclear spin equal to
1
2 0 1
3
2
3
xii) The stretching frequency of chromophore is than that
of C C.
more less half equal
xiii) In NMR spectroscopy, absorption of long wavelength radio frequency
radiations by molecule causes change in
Electronic state
Vibrational state
Rotational state
Spin state
xiv) For a non-linear molecule the number of fundamental modes of vibrations
are calculated by the relation
3N 3N 5
3N 6 3N 2
SLR-SB 51 *SLRSB51*
Set P
2. Answer any seven of the following 14
Calculate the modes of vibration in CO2 molecule.
ii) What is delta scale and Tau scale
iii) Deifne the term
bathochromic shift
hypsochromic shift.
iv) Predict the frequency shift of the carbonyl absorption in the following
aldehyde.

II)
Define coupling constant with example.
vi) What is magnetic nuclei and non magnetic nuclei
vii) Define parent ion and fragment ion.
viii) Name the different transitions involved in UV spectroscopy.
ix) Explain peak area.
3. Write short notes on (any two) 10
Why tetramethyl silane is used as internal reference in NMR
spectroscopy
ii) Explain application of mass spectroscopy.
iii) Discuss on functional group region.
State and explain Lambert's-Beer Law with mathematical expression. 4
*SLRSB51* SLR-SB 51
Set P
4. Answer any two of the following 14
Calculate λmax of the following compound.

II)
III)
ii) Write the different basic parts used in proton nuclear magnetic resonance
spectroscopy with schematic diagram.
iii) State Hooke's law. How it is used to calculate the vibrational frequency of
diatomic group
5. Answer any two of the following 14
State and explain the theory of mass spectrometer with diagram.
ii) Explain what types of vibrations are observed in IR spectroscopy.
iii) Define chemical shift and deduce the structure of compound with following
data
Molecular formula C4H8O
IR 1720 cm-1
M/e 88
PMR 2.7 2H)
1.05
1.12 3H)