Atomic and Molecular Physics MCQs with Answers 2027

Q21

If the wavelength of the first line of the Balmer series in the hydrogen spectrum is

λ

, then the wavelength of the first line of the Lyman series is

Select an option to see the answer and solution.

Q22

Open question

For a diatomic molecule with the vibrational quantum number n and rotational quantum number J, the vibrational level spacing ΔE_n = E_n - E_{n - 1} and the rotational level spacing ΔE_J - E_J - E_{J - 1} are approximately

Select an option to see the answer and solution.

Q23

Open question

If R₁ is the value of the Rydberg constant assuming mass of the nucleus to be infinitely large compared to that of an electron, and if R₂ is the Rydberg constant taking nuclear mass to be 7500 times the mass of the electron, then the ratio

\frac{R _{2}}{R _{1}}

is

Select an option to see the answer and solution.

Q24

Open question

Three values of rotational energies of molecules are given below in different units
P = 10 cm^-1
Q = 10^-23 J
R = 10⁴ MHz
Choose the correct arrangement in the increasing order of energy.

Select an option to see the answer and solution.

Q25

Open question

The coherence length of laser light is

Select an option to see the answer and solution.

Q26

Open question

The spectral terms for a certain electronic configuration are given by ³d, ¹d, ³p, ¹p, ⁵s, ³s. The term with the lowest energy is

Select an option to see the answer and solution.

Q27

Open question

In accordance with the selection rules of electric dipole transitions, the 4³p₁ state of helium can decay by photon emission to the states

Select an option to see the answer and solution.

Q28

Open question

Light of wavelength 1.5 μm incident on a material with a characteristic Raman frequency of 20 × 10¹² Hz results in a Stokes-shifted line of wavelength
[Given : c = 3 × 10⁸ m/s]

Select an option to see the answer and solution.

Q29

Open question

In the linear Stark effect, the application of an electric field

Select an option to see the answer and solution.

Q30

Open question

Consider the pure rotational spectrum of a diatomic rigid rotor. The separation between two consecutive lines

Δ v

in the spectrum

Select an option to see the answer and solution.

Q31

Open question

If an atom is in the ³d₃ state, the angle between its orbital and spin angular momentum vectors (

L

and

S

) is

Select an option to see the answer and solution.

Q32

Open question

Which one of the following statements is incorrect in vibrational spectroscopy with anharmonicity?

Select an option to see the answer and solution.

Q33

Open question

The pure rotational level of a molecule in the far-infrared region follows the formula F(J) = BJ(J + 1), where F(J) is the energy of the rotational level with quantum number J and B is the rotational constant. The lowest rotational energy gap in rotational Raman spectrum is

Select an option to see the answer and solution.

Q34

Open question

Caesium has a nuclear spin of 7/2. The hyperfine spectrum of the d lines of the caesium atom will consist of

Select an option to see the answer and solution.

Q35

Open question

The degeneracy of an excited state of nitrogen atom having electronic configuration 1s² 2s² 2p² 3d¹ is

Select an option to see the answer and solution.

Q36

Open question

The population inversion in a two-level laser material cannot be achieved by optical pumping because

Select an option to see the answer and solution.

Q37

Open question

Group I lists some physical phenomena while Group II gives some physical parameters. Match the phenomenon with the corresponding parameter

Group I	Group II
P. Doppler broadening	1. Moment of inertia
Q. Natural broadening	2. Refractive index
R. Rotational spectrum	3. Lifetime of the energy level
S. Total internal reflection	4. Pressure

Select an option to see the answer and solution.

Q38

Open question

The Lande g factor for the level ³d₃ is

Select an option to see the answer and solution.

Q39

Open question

In a Raman scattering experiment, light of frequency

ν

from a laser is scattered by diatomic molecules having the moment of inertia

I

. The typical Raman shifted frequency depends on

Select an option to see the answer and solution.

Q40

Open question

CO₂ molecule has the first few energy levels uniformly separated by approximately 2.5 meV. At a temperature of 300 K, the ratio of the number of molecules in the 4^th excited state to the number in the 2^nd excited state is about

Select an option to see the answer and solution.

Atomic and Molecular Physicspractice.

Atomic and Molecular Physics
practice.