Q.No:1 CSIR Dec-2014
An atomic transition \({}^1 P\to {}^1 S\) in a magnetic field \(1\) Tesla shows Zeeman splitting. Given that the Bohr magneton \(\mu_B=9.27 \times 10^{-24} J/T\), and the wavelength corresponding to the transition is \(250 nm\), the separation in the Zeeman spectral lines is approximately
(1)
\(0.01 nm\)
(2)
\(1.0 nm\)
(3)
\(0.1 nm\)
(4)
\(10 nm\)
Check Answer
Option 1
Q.No:2 CSIR June-2015
Of the following term symbols of the \(np^2\) atomic configurations, \({ }^{1} \mathrm{S}_{0}, { }^{3} \mathrm{P}_{0}, { }^{3} \mathrm{P}_{1},{ }^{3} \mathrm{P}_{2}\) and \({ }^{3} \mathrm{D}_{1}\) which is the ground state ?
(1)
\({ }^{3} \mathrm{P}_{0}\)
(2)
\({ }^{3} \mathrm{S}_{0}\)
(3)
\({ }^{3} \mathrm{P}_{2}\)
(4)
\({ }^{3} \mathrm{P}_{1}\)
Check Answer
Option 1
Q.No:3 CSIR Dec-2015
The \(LS\) configurations of the ground state of \({^{12}Mg}, {^{13}Al}, {^{17}Cl}\) and \({^{18}Ar}\) are, respectively,
(1)
\({}^{3} S_1, {}^{2} P_{1/2}, {}^{2} P_{1/2}\) and \({}^{1} S_0\)
(2)
\({}^{3} S_1, {}^{2} P_{3/2}, {}^{2} P_{3/2}\) and \({}^{3} S_1\)
(3)
\({}^{1} S_0, {}^{2} P_{1/2}, {}^{2} P_{3/2}\) and \({}^{1} S_0\)
(4)
\({}^{1} S_0, {}^{2} P_{3/2}, {}^{2} P_{1/2}\) and \({}^{3} S_1\)
Check Answer
Option 3
Q.No:4 CSIR June-2016
The ground state electronic configuration of \({^{22}Ti}\) is \([{Ar}]3d^2 4s^2\). Which state, in the standard spectroscopic notations, is not possible in this configuration?
(1)
\({}^1 F_3\)
(2)
\({}^1 S_0\)
(3)
\({}^1 D_2\)
(4)
\({}^3 P_0\)
Check Answer
Option 1
Q.No:5 CSIR June-2016
In a normal Zeeman effect experiment using a magnetic field of strength \(0.3 T\), the splitting between the components of a \(660 nm\) spectral line is
(1)
\(12 pm\)
(2)
\(10 pm\)
(3)
\(8 pm\)
(4)
\(6 pm\)
Check Answer
Option 4
Q.No:6 CSIR Dec-2016
In the \(L\)-\(S\) coupling scheme, the terms arising from two non-equivalent \(p\)-electrons are
(1)
\({}^3 S, {}^1 P, {}^3 P, {}^1 D, {}^3 D\)
(2)
\({}^1 S, {}^3 S, {}^1 P, {}^1 D\)
(3)
\({}^1 S, {}^3 S, {}^3 P, {}^3 D\)
(4)
\({}^1 S, {}^3 S, {}^1 P, {}^3 P, {}^1 D, {}^3 D\)
Check Answer
Option 4
Q.No:7 CSIR June-2017
An atomic spectral line is observed to split into nine components due to Zeeman shift. If the upper state of the atom is \({}^3 D_2\) then the lower state will be
(1)
\({}^3 F_2\)
(2)
\({}^3 F_1\)
(3)
\({}^3 P_1\)
(4)
\({}^3 P_2\)
Check Answer
Option 3
Q.No:8 CSIR June-2017
If the binding energies of the electron in the K and L shells of silver atom are \(25.4 keV\) and \(3.34 keV\), respectively, then the kinetic energy of the Auger electron will be approximately
(1)
\(22 keV\)
(2)
\(10.5 keV\)
(3)
\(9.3 keV\)
(4)
\(18.7 keV\)
Check Answer
Option 4
Q.No:9 CSIR Dec-2017
The Zeeman shift of the energy of a state with quantum numbers \(L, S, J\) and \(m_J\) is
\[
H_Z=\frac{m_J \mu_B B}{J(J+1)}(\langle \mathbf{L}\cdot \mathbf{J}\rangle+g_S\langle \mathbf{S}\cdot \mathbf{J}\rangle)
\]
where \(B\) is the applied magnetic field, \(g_S\) is the \(g\)-factor for the spin and \(\mu_B/h=1.4\) MHz-\(G^{-1}\), where \(h\) is the Planck constant. The approximate frequency shift of the \(S=0, L=1\) and \(m_J=1\) state, at a magnetic field of \(1 G\), is
(1)
\(10 MHz\)
(2)
\(1.4 MHz\)
(3)
\(5 MHz\)
(4)
\(2.8 MHz\)
Check Answer
Option 2
Q.No:10 CSIR Dec-2017
The separations between the adjacent levels of a normal multiplet are found to be \(22 cm^{-1}\) and \(33 cm^{-1}\). Assume that the multiplet is described well by the \(L\)-\(S\) coupling scheme and the Lande's interval rule, namely \(E(J)-E(J-1)=AJ\), where \(A\) is a constant. The term notations for this multiplet is
(1)
\({}^3 P_{0, 1, 2}\)
(2)
\({}^3 F_{2, 3, 4}\)
(3)
\({}^3 G_{3, 4, 5}\)
(4)
\({}^3 D_{1, 2, 3}\)
Check Answer
Option 4
Q.No:11 CSIR Dec-2017
If the fine structure splitting between the \(2^2 P_{3/2}\) and \(2^2 P_{1/2}\) levels in the hydrogen atom is \(0.4 cm^{-1}\), the corresponding splitting in \({Li^{2+}}\) will approximately be
(1)
\(1.2 cm^{-1}\)
(2)
\(10.8 cm^{-1}\)
(3)
\(32.4 cm^{-1}\)
(4)
\(36.8 cm^{-1}\)
Check Answer
Option 3
Q.No:12 CSIR June-2018
A photon of energy \(115.62 keV\) ionizes a K-shell electron of a \({Be}\) atom. One L-shell electron jumps to the K-shell to fill this vacancy and emits a photon of energy \(109.2 keV\) in the process. If the ionization potential for the L-shell is \(6.4 keV\), the kinetic energy of the ionized electron is
(1)
\(6.42 keV\)
(2)
\(12.82 keV\)
(3)
\(20 keV\)
(4)
\(32 cm^{-1}\)
Check Answer
Option 3
Q.No:13 CSIR June-2018
The value of the Lande \(g\)-factor for a fine-structure level defined by the quantum numbers \(L=1, J=2\) and \(S=1\), is
(1)
\(11/6\)
(2)
\(4/3\)
(3)
\(8/3\)
(4)
\(3/2\)
Check Answer
Option 4
Q.No:14 CSIR June-2019
A doubly charged ion in the angular momentum state (\(J=2, J_3=1\)) meets a gas of polarized electrons (\(S_3=1/2\)) and gets neutralized. If the orbital angular momentum transferred in the process is zero, the probability that the neutral atom is in the (\(J=2, J_3=2\)) state is
(1)
\(2/5\)
(2)
\(2/3\)
(3)
\(1/5\)
(4)
\(1/3\)
Check Answer
Option 4
Q.No:15 CSIR June-2020
The wavelength of the first Balmer line of hydrogen is \(656 nm\). The wavelength of the corresponding line for a hydrogenic atom with \(Z=6\) and nuclear mass of \(19.92\times 10^{-27} kg\) is
(a)
\(18.2 nm\)
(b)
\(109.3 nm\)
(c)
\(143.5 nm\)
(d)
\(393.6 nm\)
Check Answer
Option a
Q.No:16 CSIR Feb-2022
Diffuse hydrogen gas within a galaxy may be assumed to follow a Maxwell distribution at
temperature \(10^6\) K , while the temperature appropriate for the \(H\) gas in the inter-galactic space,
following the same distribution, may be taken to be \(10^4\) K . The ratio of thermal broadening \(\delta v_G/\delta v_{IG}\) of the Lyman-\(\alpha\) line from the \(H\) -atoms within the galaxy to that from the intergalactic space is closest to
(1)
\(100\)
(2)
\(1/100\)
(3)
\(10\)
(4)
\(1/10\)
Check Answer
Option 3
Q.No:17 CSIR Sep-2022
The electronic configuration of \(^{12}C\) is \(1s^2, 2s^2, 2p^2\). Including LS coupling, the correct ordering of it's energy is
(1)
\(E(^3P_2)<E(^3P_1)<E(^3P_0)<E(^1D_2)\),
(2)
\(E(^3P_0)<E(^3P_1)<E(^3P_2)<E(^1D_2)\),
(3)
\(E(^1D_2)<E(^3P_2)<E(^3P_1)<E(^3P_0)\),
(4) \(E(^3P_1)<E(^3P_0)<E(^3P_2)<E(^1D_2)\),
Check Answer
Option 2
Q.No:18 CSIR Sep-2022
In the absorption spectrum of H-atom, the frequency of transition from the ground state to the first excited state is \(\nu_H\). The corresponding frequency for a bound state of a positively charged muon \(\mu^+\) and an electron is \(\nu_\mu\). Using \(m_\mu=10^{-28}kg\), \(m_e=10^{-30}kg\) and \(m_p>>m_e,m_\mu\), the value of \(\frac{\nu_{\mu} - \nu_H}{\nu_H} \)
(1)
0.001
(2)
–0.001
(3)
-0.01
(4)
0.01
Check Answer
Option 3
Q.No:19 CSIR June-2023
The red line of wavelength \(644 \hspace{1mm}nm\) in the emission spectrum of Cd corresponds to a transition from the \(^1D_2\) level to the \(^1P_1\) level. In the presence of a weak magnetic field, this spectral line will split into (ignore hyperfine structure)
1) 9 lines
2) 6 lines
3) 3 lines
4) 2 lines
Check Answer
Option 3
Q.No:20 CSIR Dec-2023
The Hamiltonian for two particles with angular momentum quantum numbers \( l_1 = l_2 = 1 \), is
\[
\hat{H} = \frac{\epsilon}{\hbar^2} \left[ (\hat{L}_1 + \hat{L}_2) \cdot \hat{L}_2 - (\hat{L}_{1z} + \hat{L}_{2z})^2 \right].
\]
If the operator for the total angular momentum is given by \( \hat{L} = \hat{L}_1 + \hat{L}_2 \), then the possible energy eigenvalues for states with \( l = 2 \), (where the eigenvalues of \( \hat{L}^2 \) are \( l(l + 1)\hbar^2 \)) are
1) \( 3\epsilon, 2\epsilon, -\epsilon \)
2) \( 6\epsilon, 5\epsilon, 2\epsilon \)
3) \( 3\epsilon, 2\epsilon, \epsilon \)
4) \( -3\epsilon, -2\epsilon, \epsilon \)
Check Answer
Option 1
Q.No:21 CSIR Dec-2023
The ionization potential of hydrogen atom is 13.6 eV, and \( \lambda_H \) and \( \lambda_D \) denote longest wavelengths in Balmer spectrum of hydrogen and deuterium atoms, respectively. Ignoring the fine and hyperfine structures, the percentage difference \( y = \frac{\lambda_H - \lambda_D}{\lambda_H} \times 100 \), is closest to
1) 1.0003 %
2) -0.03 %
3) 0.03 %
4) -1.0003 %
Check Answer
Option 3
Q.No:22 CSIR Dec-2023
A solar probe mission detects a fractional wavelength shift \( \left(\frac{\Delta\lambda}{\lambda}\right) \) of the spectral line \( \lambda = 630 \) nm within a sunspot to be of the order of \( 10^{-5} \). Assuming this shift is caused by the normal Zeeman effect (i.e., neglecting other physical effects), the estimated magnetic field (in tesla) within the observed sunspot is closest to:
1) \( 3 \times 10^{-5} \)
2) \(300\)
3) \(0.3\)
4) \(3 \times 10^5\)
Check Answer
Option 3
Q.No:23 CSIR June-2024
Helium atom is excited to a state with the configuration \( (2s 2p) \) with an energy 58.3 eV. After some time, this atom spontaneously ejects a single electron. The value of the orbital angular momentum quantum number \( l \) of the ejected electron in the final state of the system is (Ionization potential of \( He(1s^2) \) is 24.6 eV):
1) \( 1 \)
2) \( 0 \)
3) \( 2 \)
4) \( 3 \)
Check Answer
Option 1
Q.No:24 CSIR June-2024
An atom of mass \( m \), initially at rest, resonantly absorbs a photon. It makes a transition from the ground state to an excited state and also gets a momentum kick. If the difference between the energies of the ground state and the excited state is \(\hbar \Delta\), the angular frequency of the absorbed photon is closest to
1) \( \Delta \left(1 + \frac{3}{2}\frac{\hbar \Delta}{mc^2}\right) \)
2) \( \Delta \left(1 + \frac{1}{2}\frac{\hbar \Delta}{mc^2}\right) \)
3) \( \Delta \left(1 + \frac{\hbar \Delta}{mc^2}\right) \)
4) \( \Delta \left(1 + 2\frac{\hbar \Delta}{mc^2}\right) \)
Check Answer
Option 2
Q.No:25 CSIR June-2024
If \(\vec{L}\) is the orbital angular momentum operator and \(\vec{\sigma}\) are the Pauli matrices, which of the following operators commutes with \(\vec{\sigma} \cdot \vec{L}\)?
1) \(\vec{L} - \frac{\hbar}{2} \vec{\sigma}\)
2) \(\vec{L} + \frac{\hbar}{2} \vec{\sigma}\)
3) \(\vec{L} + \hbar \vec{\sigma}\)
4) \(\vec{L} - \hbar \vec{\sigma}\)
Check Answer
Option 2
Q.No:26 CSIR Dec-2024
The hyperfine splitting of the ground state of the hydrogen atom is given as
\[
\Delta E \propto \frac{g_p g_e}{m_p m_e a^3},
\]
where \(g_p\) and \(g_e\) are the nuclear and electron Landé \(g\)-factors respectively,
and \(a\) is the orbital radius of the ground state. It is given that
\(g_p\) (proton) = 5.59.
In hydrogen, transition between these split levels corresponds to radiation
of wavelength \(21\ \text{cm}\).
If the proton is replaced by a positron, the corresponding wavelength would be
1) \(2.6\ \text{mm}\)
2) \(3.2\ \text{mm}\)
3) \(3.2\ \text{cm}\)
4) \(2.6\ \text{cm}\)
Check Answer
Option 1
Q.No:27 CSIR Dec-2024
Consider the Bromine ion \( \mathrm{Br}^+ \) in its ground state.
The atomic number of Br is 35.
The fine-structure term symbol \((^{2S+1}L_J)\) under the LS coupling scheme
for the lowest energy state of this ion would be
1) \(^{3}P_{2}\)
2) \(^{3}P_{0}\)
3) \(^{1}D_{2}\)
4) \(^{4}S_{3/2}\)
Check Answer
Option 1
Q.No:28 CSIR Dec-2024
A hydrogen atom, excited to the electronic configuration \(3S_{1/2}\)
(\(nL_J\) notation), relaxes to the ground state via electric dipole
transitions.
Considering only fine structure and ignoring hyperfine structure,
the maximum number of emitted spectral lines is
1) 3
2) 6
3) 1
4) 4
Check Answer
Option 4
Q.No:29 CSIR June-2025
An atom is subjected to a weak magnetic field \(B = 0.1\,\text{T}\).
A spectral line of wavelength \(184.9\,\text{nm}\) corresponding to a
\(J = 1 \rightarrow J = 0\) transition splits into three components.
The highest and the lowest components are separated by
\(3.2 \times 10^{-4}\,\text{nm}\).
The magnetic moment of the atom in the \(J = 1\) state
(in units of the Bohr magneton \(\mu_B\)) is
1) 2.82
2) 0.71
3) 1.41
4) 4.23
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