Frage 1
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In the Bohr model of the hydrogen atom, let R, V and E represent the radius of the orbit, the speed of electron and the total energy of the electron respectively. Which of the following quantity is proportional to the quantum number n?
Frage 2
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The work function for aluminium is 4.125 eV. The cut off wavelength for photoelectric effect for Aluminium is
Antworten
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200 nm
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300 nm
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150 nm
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420 nm
Frage 3
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The electron is a hydrogen atom makes a transition from n = n1 to n = n2 state. The time period of the electron in the final state is eight times that in the initia state. Then the possible values of n1 and n2 are
Antworten
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n1 = 8, n2 = 2
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n1 = 4, n2 = 2
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n1 = 6, n2 = 2
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n1 = 1, n2 = 2
Frage 4
Frage
Light of frequency 1.5 times the threshold frequency is incident on photosensitive material. If the frequency is halved and intensity is doubled, the photocurrent becomes
Antworten
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Quadrupled
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Doubled
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Zero
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Halved
Frage 5
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A radioactive substance has a half life of four months. Three fourth of the substance will decay in
Antworten
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12 months
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4 months
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8 months
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3 months
Frage 6
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A radio isotope has a half life of 5 years. The fraction of the atoms of this material that would decay in 15 years will be
Frage 7
Frage
When Boron 5B10 is bombarded by neutron, particles are emitted. The resulting nucleus has mass number
Frage 8
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Tracer techniques make use of
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neutron scattering
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electron beams
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lasers
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radioactive isotopes
Frage 9
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A sample of radioactive substance contains 2,828 atoms. If its half life is two days, how many atoms will be left intact in the sample after one day?
Frage 10
Frage
The unit of Planck’s constant is
Frage 11
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Mean life of a radioactive element is one year. Then its half life is (years)
Frage 12
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Hydrogen atom emits blue light when it jumps from n = 4 energy level to the n = 2 energy level. Which colour of light would the atom emit when it jumps from the n = 5 level to the n = 2 level?
Frage 13
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The electromagnetic theory of light was developed by
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Max Planck
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Maxwall
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Newton
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Huygens
Frage 14
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The concept of quantum nature of light has emerged in an attempt to explain
Frage 15
Frage
The electron in the innermost orbit of an atom has _____ velocity.
Frage 16
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Einstein’s photoelectric equation was experimentally verified by
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Millikan
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Rutherford
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Einstein
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Fermi
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all the above
Frage 17
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A photon of energy 8 eV is incident on a metal surface of threshold frequency 1.6 1015 Hz. The K.E of the photoelectrons emitted (in eV) (Take h = 6 10–34 Js)
Frage 18
Frage
TV waves have a wavelength range of 1-10 metre. This frequency range in MHz is
Antworten
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3 – 3000
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300 – 3000
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3 – 30
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30 – 300
Frage 19
Frage
. An electron and a proton have the same de-Broglie wavelength. Then the kinetic energy of the electron is
Frage 20
Frage
Whenever a hydrogen atom emits a photon in the Balmer series
Antworten
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It may emit another photon in the Balmer series
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It must emit another photon in the Lyman series
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It may emit another photon in the Paschen series
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It need not emit any more photon
Frage 21
Frage
The de Broglie wavelength of an electron in the first Bohr orbit is
Antworten
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equal to the circumference of the first orbit
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equal to twice the circumference of the first orbit
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equal to half the circumference of the first orbit
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equal to one fourth the circumference of the first orbit