Q83 · CSIR NET Chemistry, June 2013
Paper: CSIR NET June 2013 · Subject: Physical Chemistry · Chapter: Molecular Spectroscopy · Topic: Raman · Marks: 2 · Difficulty: Medium
A triatomic molecule of the type $\mathrm{AB_2}$ shows two IR absorption lines and one IR-Raman line. The structure of the molecule is:
(a)B-B-A
(b)B-A-B
(c)
(d)
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
Linear B–A–B (D∞h) has a centre of symmetry. Its asymmetric stretch and bend are IR-active and the symmetric stretch is Raman-active only (mutual exclusion), so 2 IR + 1 Raman (b).
Study loop for Molecular Spectroscopy