Atomic And Molecular Physics — Part 1 MCQs with Explanations

Infrared spectra is the correct answer to “All vibrations producing a change in the electric dipole moment of a molecule yield”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

$$\frac{{{g_1}e{H_0}}}{{4\pi {m_p}}}$$ is the correct answer to “A piece of paraffin is placed in a uniform magnetic field H 0 . The sample contains hydrogen nuclei of mass m p , which interact only with external magnetic field. An additional oscillating magnetic field is applied to observe resonance absorption. If g 1 is the g-factor of the hydrogen nucleus, the frequency at which resonance absorption takes place, is given by”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

P, S and T is the correct answer to “Consider the following statements about molecular spectra: P. CH 4 does not give pure rotational Raman lines Q. SF 6 could be studied by rotational Raman spectroscopy R. N 2 shows infrared absorption spectrum S. CH 3 CH 3 shows vibrational Raman and infrared absorption lines T. H 2 O 2 shows pure rotational spectrum Choose the right combination of correct statements.”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

4 states is the correct answer to “The hyperfine structure of Na(3 2 P 3/2 ) with nuclear $$l$$ = 3/2 has”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

3 is the correct answer to “The number of hyperfine components observed in the electronic transition $${}^2{p_{\frac{1}{2}}} \to {}^2{s_{\frac{1}{2}}}$$ of an atom with nuclear spin $$\frac{1}{2}$$ is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

$${}^4{f_{\frac{9}{2}}}$$ is the correct answer to “The spectral term for the atom with 70% filled subshell and only s = $$\frac{3}{2}$$ is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

3 is the correct answer to “A system has energy level E 0 , 2E 0 , 3E 0 , . . . . . , where the excited states are triply degenerated. Four non-interacting bosons are placed in this system. If the total energy of these bosons is 5E 0 , the number of microstates is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

60 cm-1 is the correct answer to “The far infrared rotational absorption spectrum of a diatomic molecule shows equidistant lines with spacing 20 cm -1 . The position of the first stokes line in the rotational Raman spectrum of this molecule is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

$$\frac{{{\hbar ^2}}}{{2I}}l\left( {l + 1} \right) + \frac{{{\hbar ^2}m_l^2}}{2}\left( {\frac{1}{{{I_z}}} - \frac{1}{I}} \right)$$ is the correct answer to “The three principal moments of inertia of a methanol (CH 3 OH) molecule have the property $${I_x} = {I_y} = I$$ and $${I_z} \ne I.$$ The rotational energy eigenvalues are”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

12 is the correct answer to “The total number of Zeeman components observed in an electronic transition $${}^2{d_{\frac{5}{2}}} \to {}^2{p_{\frac{3}{2}}}$$ of an atom in a weak field is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

three : 1 is Raman active and 2 are infrared active is the correct answer to “The number of fundamental vibrational modes of CO 2 molecule is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

infrared range of frequencies is the correct answer to “The spectrum of radiation emitted by a black body at a temperature 1000 K peaks in the”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

$$\frac{3}{2}$$ is the correct answer to “The Lande g-factor for the $${}^3{p_1}$$ level of an atom is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

E2 → E1 is the correct answer to “A three-level system of atoms has N 1 atoms in level E 1 , N 2 in level E 2 and N 3 in level E 3 (N 2 > N 1 > N 3 and E 1 < E 2 < E 3 ). Lasere mission is possible between the levels”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

np and 2s, n > 2 is the correct answer to “The principal series of spectral lines of lithium is obtained by transitions between”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

2$$l$$ + 1 is the correct answer to “An atom with one outer electron having orbital angular momentum $$l$$ is placed in a weak magnetic field. The number of energy levels into which the higher total angular momentum state splits, is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

Ne only is the correct answer to “In a He-Ne laser, the laser transition takes place in”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

6s → 5p is the correct answer to “Which one of the following electronic transitions in neon is not responsible for LASER action in a helium-neon laser”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

15 cm-1 is the correct answer to “The spin-orbit coupling constant for the upper state of sodium atom which emits D lines of wave numbers 16956.2 and 16973.4 cm -1 is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

$$\frac{5}{{27}}\lambda $$ is the correct answer to “If the wavelength of the first line of the Balmer series in the hydrogen spectrum is $$\lambda $$, then the wavelength of the first line of the Lyman series is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

ΔEn = constant, ΔEJ = constant is the correct answer to “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”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

a little less than unity is the correct answer to “If R 1 is the value of the Rydberg constant assuming mass of the nucleus to be infinitely large compared to that of an electron, and if R 2 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”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

R, Q, P is the correct answer to “Three values of rotational energies of molecules are given below in different units P = 10 cm -1 Q = 10 -23 J R = 10 4 MHz Choose the correct arrangement in the increasing order of energy.”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

directly proportional to the length of the active lasing medium is the correct answer to “The coherence length of laser light is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

5s is the correct answer to “The spectral terms for a certain electronic configuration are given by 3 d, 1 d, 3 p, 1 p, 5 s, 3 s. The term with the lowest energy is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

23s1, 33d2 and 33d1 is the correct answer to “In accordance with the selection rules of electric dipole transitions, the 4 3 p 1 state of helium can decay by photon emission to the states”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

1.67 μm is the correct answer to “Light of wavelength 1.5 μm incident on a material with a characteristic Raman frequency of 20 × 10 12 Hz results in a Stokes-shifted line of wavelength [Given : c = 3 × 10 8 m/s]”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

partially lifts the degeneracy of n = 2 level on hydrogen atom and splits n = 2 level into three levels is the correct answer to “In the linear Stark effect, the application of an electric field”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

is inversely proportional to the moment of inertia of the rotor is the correct answer to “Consider the pure rotational spectrum of a diatomic rigid rotor. The separation between two consecutive lines $$\Delta \overline v $$ in the spectrum”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

$${\cos ^{ - 1}}\frac{1}{{\sqrt 3 }}$$ is the correct answer to “If an atom is in the 3 d 3 state, the angle between its orbital and spin angular momentum vectors ($$\overrightarrow {\bf{L}} $$ and $$\overrightarrow {\bf{S}} $$) is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

The intensities of hot band lines are stronger than the fundamental absorption is the correct answer to “Which one of the following statements is incorrect in vibrational spectroscopy with anharmonicity”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

4B is the correct answer to “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”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

10 lines is the correct answer to “Caesium has a nuclear spin of 7/2. The hyperfine spectrum of the d lines of the caesium atom will consist of”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

10 is the correct answer to “The degeneracy of an excited state of nitrogen atom having electronic configuration 1s 2 2s 2 2p 2 3d 1 is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

the rate of upward transitions is equal to the rate of downward transitions is the correct answer to “The population inversion in a two-level laser material cannot be achieved by optical pumping because”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

P-4, Q-3, R-1, S-2 is the correct answer to “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”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

$$\frac{3}{2}$$ is the correct answer to “The Lande g factor for the level 3 d 3 is”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

only $$I$$ is the correct answer to “In a Raman scattering experiment, light of frequency $$\nu $$ from a laser is scattered by diatomic molecules having the moment of inertia $$I$$. The typical Raman shifted frequency depends on”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

0.9 is the correct answer to “CO 2 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”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.

12B is the correct answer to “The separation between the first stokes and corresponding anti-stokes Iines of the rotational Raman spectrum in terms of the rotational constant B”. This question is standard in competitive examination syllabi for Atomic And Molecular Physics.