Order Magnetic Quantum Number Assignment

Order Magnetic Quantum Number Assignment
54. The number of revolutions made by an electron per second in the third orbit of hydrogen atom is (In the first orbit of
hydrogen atom, velocity = 2.18 u 106
m/s and radius = 0.53 Å)
(a) 2.42 u 1014 (b) 2.42 u 106
(c) 2.42 u 1010 (d) 2.42 u 104
55. The velocity of an electron in a Bohr orbit is directly proportional to
(a) atomic number of the atomic species
(b) quantum number of the orbit
(c) square of the quantum number of the orbit
(d) mass of the electron
56. Photoelectric effect is observed only in metals and not in non metals because
(a) Non-metals have very high ionization energy
(b) Non-metals occur only in combined state
(c) In non metals last electron enters ‘p’ orbital
(d) Non-metals generally have low atomic weight
57. Radiation of energy 8 eV is incident on a metal surface. If its work function is 3.5eV, the stopping potential is
(a) 4.5 V (b) 3.5 V (c) 11.5 V (d) 3.5 V
58. A particle, for which mass and velocity are numerically equal, moves with a de Broglie wavelength of 165 Å. Its kinetic
energy is
(a) 6.25 u 1037 (b) 4 u 1039 J (c) 6.25 u 1037 J (d) 4 u 1026J
59. An electron and proton are travelling such that their wavelengths are in the ratio 1 : 2. Their momentum are in
the ratio
(a) 1836 : 1 (b) 2 u 1836 : 1 (c) 1 : 1836 (d) 2 : 1
Order Magnetic Quantum Number Assignment
60. The de Broglie wavelength of a proton at 27qC moving with rms velocity is (mass of proton = 1.67 u 1027 kg)
(a) 45.68 Å (b) 145 Å (c) 1.45 Å (d) 2413 Å
61. The kinetic energy of a moving particle is 2.5 u 1028 J. The frequency (in s1
) of this particle is
(a) 1.25 u 105
(b) 7.5 u 105
(c) 1.25 u 106
(d) 5.2 u 106
62. The Heisenberg’s uncertainity principle was experimentally verified by
(a) Davison Germer experiment (b) Compton effect
(c) Zeeman effect (d) Photoelectric effect
63. It is not possible to build an instrumental device that can defy Heisenberg uncertainty principle by reducing the error
because
(a) position and momentum are conjugate pair of variables
(b) velocity can be measured only along one axis
(c) to observe the electron it has to be illuminated
(d) as mass of particle increases, uncertainty decreases
64. We can talk only in terms of probability of finding an electron around the nucleus because
(a) position has to be determined along three axes
(b) both exact position and exact velocity cannot be determined simultaneously
(c) electron has both wave like and matter like behaviour
(d) the electrons have a spin