11312394
Descripción
Test por raghu Katagall, actualizado hace más de 1 año
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Creado por raghu Katagall
hace más de 6 años
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Pregunta 1
Pregunta
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?
Respuesta
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VR
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RE
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E/V
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R/E
Pregunta 2
Pregunta
The work function for aluminium is 4.125 eV. The cut off wavelength for photoelectric effect for Aluminium is
Respuesta
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200 nm
-
300 nm
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150 nm
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420 nm
Pregunta 3
Pregunta
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
Respuesta
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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
Pregunta 4
Pregunta
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
Respuesta
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Quadrupled
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Doubled
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Zero
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Halved
Pregunta 5
Pregunta
A radioactive substance has a half life of four months. Three fourth of the substance will decay in
Respuesta
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12 months
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4 months
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8 months
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3 months
Pregunta 6
Pregunta
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
Respuesta
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1
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2/3
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7/8
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5/8
Pregunta 7
Pregunta
When Boron 5B10 is bombarded by neutron, particles are emitted. The resulting nucleus has mass number
Respuesta
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11
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6
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7
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15
Pregunta 8
Pregunta
Tracer techniques make use of
Respuesta
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neutron scattering
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electron beams
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lasers
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radioactive isotopes
Pregunta 9
Pregunta
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?
Respuesta
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2,000
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1,000
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1,414
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707
Pregunta 10
Pregunta
The unit of Planck’s constant is
Respuesta
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Nm
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eV
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Js–1
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Js
Pregunta 11
Pregunta
Mean life of a radioactive element is one year. Then its half life is (years)
Respuesta
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0.5
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0.4
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1
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0.693
Pregunta 12
Pregunta
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?
Respuesta
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Red
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Yellow
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Green
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Violet
Pregunta 13
Pregunta
The electromagnetic theory of light was developed by
Respuesta
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Max Planck
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Maxwall
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Newton
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Huygens
Pregunta 14
Pregunta
The concept of quantum nature of light has emerged in an attempt to explain
Respuesta
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black – body radiation
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photoelectric effect
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polarisation of light
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interference and diffraction.
Pregunta 15
Pregunta
The electron in the innermost orbit of an atom has _____ velocity.
Respuesta
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mean
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zero
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highest
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lowest
Pregunta 16
Pregunta
Einstein’s photoelectric equation was experimentally verified by
Respuesta
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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
Pregunta 17
Pregunta
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)
Respuesta
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2
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1.2
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1.6
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6
Pregunta 18
Pregunta
TV waves have a wavelength range of 1-10 metre. This frequency range in MHz is
Respuesta
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3 – 3000
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300 – 3000
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3 – 30
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30 – 300
Pregunta 19
Pregunta
. An electron and a proton have the same de-Broglie wavelength. Then the kinetic energy of the electron is
Respuesta
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greater than the kinetic energy of the proton
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zero
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Infinity
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equal to the kinetic energy of the proton
Pregunta 20
Pregunta
Whenever a hydrogen atom emits a photon in the Balmer series
Respuesta
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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
Pregunta 21
Pregunta
The de Broglie wavelength of an electron in the first Bohr orbit is
Respuesta
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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
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