Indian Forest Service (Mains), Chemistry optional · 2023 · Paper II
Q6(f). Isotopic substitution in rotational spectra
Question
How does isotopic substitution affect the rotational spectrum of a diatomic molecule?
Answer in brief
A heavier isotope increases reduced mass and moment of inertia, lowering the rotational constant and compressing the spectrum.
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Coversrotational spectroscopyisotopic substitutionrotational constantreduced massrigid rotor
All parts of Question 6
- 6(a) Selective reduction and alpha oxidation10 marks
- 6(b) Photochemical alpha cleavage10 marks
- 6(c) Two C3H6O carbonyl compounds5 marks
- 6(d) Meaning of a coupling constant5 marks
- 6(e) Intensity of alkene and ketone UV absorption5 marks
- 6(f) Isotopic substitution in rotational spectra5 marks