Question

38 : Identify which of the following pairs of molecules
exhibit both a pure rotational spectrum and a rotational
Raman spectrum
2517152653
0, and H20
CO2 and No
CO and CH
NO and DCCH​

Answer 1

Answer:co2 and n2o

Explanation:

Answer 2

The correct answer to this question is option 4. NO and DCCH.

Explanation:

• It is given that for any molecule to show a pure rotational spectrum, it should have a permanent electric dipole.  

• And for a molecule to exhibit a rotational Raman spectrum, its polarizability must be anisotropic i.e. not be alike in all directions.  

• Thus, O2, CO2, N2O will all fail to demonstrate a pure rotational spectrum.

• Even though CH4 is non-polar, it does exhibit a weak rotational spectrum because it distorts under the impact of centrifugal forces when rotating around one of the C-H bonds and develops into a symmetric rotor.

• All of the molecules given in the options possess anisotropic polarizability but CH4 and thus the only pair of molecules to exhibit both a pure rotational spectrum and a rotational Raman spectrum are NO and DCCH.