ATOMIC AND MOLECULAR PHSICS (PREVIOUS SET QUESTIONS )

 Module 2. Atomic and Molecular Physics 

 Quantum states of an electron in an atom. Electron spin. Spectrum of helium and alkali atom. Relativistic corrections for energy levels of hydrogen atom, hyperfine structure and isotopic shift, width of spectrum lines , LS & JJ couplings. Zeeman, Paschen –Bach & Stark effects. Electron spin resonance. Nuclear magnetic resonance, chemical shift. Frank-Condon principle. Born-Oppenheimer approximation. Electronic, Rotational, Vibrational and Raman spectra of diatomic molecules, selection rules. Lasers: spontaneous and stimulated emission, Einstein A & B coefficients. Optical pumping, population inversion, rate equation. Modes of resonators and coherence length

PREVIOUS YEAR QUESTION PAPER

SET 2019/7

45. Maximum kinetic energy of photoelectron emitted from a metal when radiation of

wavelength 1200Å is 9.93 x10-19 J. The threshold wavelength for the metal is

A) 3000 Å             B) 1000 Å       C) 300 Å            D) none of these

62. Anomalous Zeeman effect is explained using the theory of ---------.

A) spin angular momenta         B) spin-orbit coupling

C) orbital angular momenta      D) variational principle

63. Energy spectrum of an unbound quantum mechanical particle is ---------.

A) continuous   B) discrete  

 C) partly continuous and discrete    D) continuous or discrete

65. In a Fourier transform spectrometer, spectra is recorded in ----------.

A) frequency domain B) time domain   C) energy domain   D) intensity domain

66. Which among the following is an example for a four level laser?

A) Ruby laser     B) CO2 laser   C) Diode laser     D) He-Ne laser

.67. Electromagnetic radiation is passing through a solution and a part of it is absorbed and the rest is transmitted. If the concentration of the solution is doubled, increase in absorption is---.

A) exactly double B) less than double  C) more than double  D) none of these

68. Which among the following is an example of a symmetric top molecule?

A) CH4    B) HCl     C) CH3F     D) H2O

69. The rotational spectral lines -------when C12is substituted by C13 in CO.

A) are shifted to lower wavenumber side

B) shifted to higher wavenumber side

C) shifted wither to lower or higher wavenumber side depending on J

D) are not shifted

70. The number of normal modes of vibration for HBr is -------.

A) 3 B) 2 C) 5 D) none of these

71. Condition for a molecular vibration to be Raman active is that -----.

A) it should be asymmetric

B) it should cause a change in polarization

C) it should cause a change in polarizability

D) it should not be IR active

72. According to Frank Condon principle electronic transition is ------that the vibrational time

period of a molecule.

A) much faster   B) slightly faster    C) much slower   D) slightly slower

73. The fine structure of E.S. R. Spectra is due to -------.

A) electron-nuclueon coupling B) orbital-spin coupling

C) electron-electron coupling D) nucleon-nucleon coupling

118. The splitting of spectral line the presence of an electric field is called -

A) Zeeman effect B) Raman effect

C) Paschen back effect D) Stark effect

120. The rotational energy levels of a linear molecule can be written as

 B) ∈= Bj(j+1) cm^-1

SET 2019/2

11. The wavelength of light emitted by an atom which is excited to higher state by 4 eV is

nearly

A) 400 nm B) 310 nm C) 280 nm D) 460 nm

12. The binding of an electron in the ground state of an atom is 24.6 eV. The total energy

required to remove both the electrons from the atom is

A) 49.2 eV      B) 98.4 eV      C) 79 eV    D) 246 eV

13. The magnetic field required to observe normal Zeeman Effect if a spectrometer can

resolve spectral lines separated by 0.45 Å at 4500 Å is

A) 3.61 T      B) 4.28 T   C) 1.26 T    D) 2.45 T

14. The frequency at which an electron with orbital magnetic moment mue precesses in a  magnetic field B is

 D)(e*B)/2*m

15. The minimum voltage that is to be applied to X-ray tube to produce X-ray photons ofwavelength 1 Å is

A) 125 MV B) 125 kV C) 66 kV D) 25 MV

16. The surface term in the semi-empirical mass formula for the binding energy of

nucleus depends on its mass number A as

A) A    B) A^2/3   C) A^-1/3    D) A^-1

17. If the wavelength of first line of Lyman series is 1215 Å, then the series limit of Lyman

series of Hydrogen spectrum is

A) 1215 Å             B) 911 Å   C) 1025 Å             D) 3820 Å

25. Which of the following is not a set of valid quantum numbers (n, l, ml, ms)

A) 1, 1, 0, ½ B) 1, 0, 0, ½ C) 3, 1, -1, ½ D) 2, 1, 0, -½

39. If a hydrogen atom at rest emits a photon of wavelength λ, then the recoil velocity the    atom of mass m is:

A) mhλ        B) mh/λ     C) h/ mλ          D) mλ/h