Q31 · CSIR NET Chemistry, December 2015
Paper: CSIR NET December 2015 · Subject: Physical Chemistry · Chapter: Molecular Spectroscopy · Topic: Rotational · Marks: 2 · Difficulty: Medium
The molecule with the smalllest rotational constant (in the microwave spectrum) among the following is
(a)$\mathrm{N \equiv CH}$
(b)$\mathrm{HC} \equiv \mathrm{CCl}$
(c)$\mathrm{CCl \equiv CF}$
(d)$\mathrm{B \equiv CCl}$
Answer
Answer: C ✓ checked by 4AB · confidence high
Explanation
The rotational constant is smallest for the largest moment of inertia — ClC≡CF, with two heavy end atoms (c).
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