JEE Questions for Physics Atoms And Nuclei Quiz 7 - MCQExams.com

An electron jumps from the 4th orbit to 2nd orbit of hydrogen atom. Given the Rydberg’s constant R = 105 cm-1, the frequency in hertz of the emitted radiation will be

  • Physics-Atoms and Nuclei-62644.png
  • 2)
    Physics-Atoms and Nuclei-62645.png

  • Physics-Atoms and Nuclei-62646.png

  • Physics-Atoms and Nuclei-62647.png
For the azimuthal quantum number l = 3, the total number of different possible values of the magnetic azimuthal quantum number, m1, is
  • 3
  • 4
  • 5
  • 7
In Fig., the energy levels of the hydrogen atom have been shown along with some transitions marked A, B, C. The transitions A, B and C respectively represent
Physics-Atoms and Nuclei-62649.png
  • the first member of the Lyman series, third member of Balmer series and second member of Paschen series.
  • The ionization potential of H, second member of Balmer series and third member of Paschen series.
  • The series limit of Lyman series, second member of Balmer series and second member of Paschen series
  • The series limit of Lyman series, third member of Balmer series and second member of Paschen series.
Ionization potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are exicted by monochromatic radiation of photon energy 12.1 eV. The spectral lines emitted by hydrogen atom according to Bohr’s theory w ill be
  • One
  • Two
  • Three
  • Four
In a hypothetical Bohr hydrogen atom, the mass of the electron is doubled. The energy E0 and radius r0 of the first orbit will be (a0 is the Bohr radius).
  • E0 = –27.2 eV ; r0 = a0 /2
  • E0 = –27.2 eV ; r0 = a0
  • E0 = –13.6 eV ; r0 = a0 /2
  • E0 = –13.6 eV; r0 = a0
If the difference of two energy states in an atom is 4eV and h/e = 4 × 10–15, then the wavelength of photon emitted as a result of the above transition will be
  • 1000 Å
  • 6000 Å
  • 3000 Å
  • 9000 Å
In a given reaction ZXA → Z+1YA → Z– 1KA – 4 → Z– 1KA – 4 radioactive radiations are emitted in the sequence of
  • α, β, γ
  • γ, α, β
  • β, α, λ
  • λ, β, α

Physics-Atoms and Nuclei-62652.png
  • 1.56 × 10–10 s–1
  • 1.56 × 10–11 s–1
  • 1.56 × 10–16 s–1
  • 1.56 × 10–17 s–1
When the number of nucleons in nuclei increase, the binding energy per nucleon
  • increases continuously with mass number
  • decreases continuously with mass number
  • remains constant with mass number
  • first increases and then decreases with increase of mass number.
Neutron decay in free space is given as follows on1 → 1H1 + –1eo + [ ]. Then the parenthesis represents a
  • Neutrino
  • Photon
  • Antineutrino
  • Graviton.
During a nuclear fusion reaction
  • A heavy nucleus breaks into two fragments by itself
  • A light nucleus bombarded by thermal neutrons breaks up
  • A heavy nucleus bombarded by thermal neutrons breaks up
  • Two light nuclei combine to give a heavier nucleus and possibly other products.
Velocities of light in vacuum and glass are represented by C and Cg. When electrons move through glass with a velocity v, there is emitted a visible radiation in glass, if
  • υ > Cg
  • u < Cg
  • u > C
  • u > Cg/C
Neutrons are more effective for producing nuclear reactions with nuclei compared to protons because
  • neutrons have more kinetic energy
  • neutrons emit beta particles
  • neutrons are unaffected by electric fields
  • neutrons are lighter than protons
The statistics obeyed by neutrino is
  • Fermi – Dirac
  • Bose – Einstein
  • Maxwell – Boltzman
  • All of the above.
Two nucleons are at a separation of 1 fm. The net force between them is F1 if both are neutrons, F2 if both are protons, and F3 if one is a proton and the other is a neutron.
  • F1 > F2 > F3
  • F2 > F1 > F3
  • F1 = F3 > F2
  • F1 = F2 > F3
The wavelength of gamma-rays is of the order of
  • 10–7 metre
  • 10–10 metre
  • 10–12 metre
  • 10–8 metre
The decay constant of a radioactive sample is λ. The half-life and mean life of the sample are respectively given by

  • Physics-Atoms and Nuclei-62654.png
  • 2)
    Physics-Atoms and Nuclei-62655.png

  • Physics-Atoms and Nuclei-62656.png

  • Physics-Atoms and Nuclei-62657.png
In the uranium radioactive series, the initial nucleus is 92U238 and that the final nucleus is 82Pb206. When uranium nucleus decays to lead, the number of α particles and β particles emitted are
  • 8α, 6 β
  • 6α, 7 β
  • 6α, 8 β
  • 4α, 3 β
The counting rate observed from a radioactive source at t = 0 second was 1600 counts per second and at t = 8 seconds, it was 100 counts per second. The counting rate observed, as counts per second at t = 6 seconds will be
  • 400
  • 300
  • 200
  • 150
The half life of At 215 is 100μ sec. If a sample contains 215 mg of At 215, the activity of the sample initially is
  • 102 Bq
  • 3 × 1010 Bq
  • 4.18 × 1024 Bq
  • 1.16 × 105 Bq
The relation between the half life T of a radioactive sample and its mean life t is
  • T = 0.693 t
  • t = 0.693 T
  • t = T
  • t = 2.718 T
A radioactive nucleus can decay simultaneously by two different processes which have decay constants λ1 and λ2. The effective decay constant of the nuclide is λ, where

  • Physics-Atoms and Nuclei-62663.png
  • 2)
    Physics-Atoms and Nuclei-62664.png

  • Physics-Atoms and Nuclei-62665.png

  • Physics-Atoms and Nuclei-62666.png
A sample of radioactive material has mass m, decay constant λ and molecular weight M. Avogadro constant = NA . The initial activity of the sample is
  • λ m
  • 2)
    Physics-Atoms and Nuclei-62667.png

  • Physics-Atoms and Nuclei-62668.png
  • m NA e λ
An element A decays into element C by a two step process
A → B2 + He4
B → C + 2e–
Then
  • A and C are isotopes
  • A and C are isobars
  • A and B are isotopes
  • A and B are isobars
If the binding energy per nucleon in 3Le7 and 2He4 nuclei are respectively 5.60 MeV and 7.06 MeV, then the energy of proton in the reaction 3Li7 → 2 2He4
  • 19.6 MeV
  • 2.4 MeV
  • 8.4 MeV
  • 17.3 MeV
Which of the following undergo fission reaction easily by slow moving neutrons?
  • U-235, P-239
  • P-239, Th-234
  • U-238, Rn-232
  • Th-234, U-238
In the Bohr’s model of hydrogen atom, the lowest orbit corresponds to
  • Infinite energy
  • The maximum energy
  • The minimum energy
  • Zero energy
Ionisation potential of Hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. The spectral lines emitted by hydrogen atoms according to Bohr’s theory will be
  • One
  • Two
  • Three
  • Four
The ratio of the frequencies of the long wavelength limits of the Lyman and Balmer series of hydrogen is
  • 27 : 5
  • 5 : 27
  • 4 : 1
  • 1 : 4
A freshly prepared radioactive substance of half life 2 hour emits radiations of density 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this substance is
  • 6 hours
  • 12 hours
  • 24 hours
  • 128 hours
92U235 and 92U238 differ as
  • 92U235 has 2 protons less
  • 92U238 has 3 protons more
  • 92U238 has 3 neutrons more
  • None of these
At any instant, the ratio of the amount of radioactive substances is 2 : 1. If their half lives be respectively 12 and 16 hours, then after two days, what will be the ratio of the substances?
  • 1 : 1
  • 2 : 1
  • 1 : 2
  • 1 : 4
If half life of radioactive atom is 2 : 3 days, then its decay constant would be
  • 0.1 day–1
  • 0.2 day–1
  • 0.3 day–1
  • 2.3 day–1
A nucleus nXm α and one β particle. The resulting nucleus is
  • nXm – 4
  • n – 2Ym – 4
  • n – 4Zm – 4
  • n – 1Zm – 4
An artificial radioactive decay series begins with unstable 94Pu241. The stable nuclide obtained after eight α-decays and five β-decays is
  • 83Br209
  • 82Pb209
  • 82Se205
  • 82Mg201
The wavelength of radiation emitted is λ0 when an electron jumps from the third to second orbit of hydrogen atom. For the electron jump from the fourth to the second orbit of the hydrogen atom, the wavelength of radiation emitted will be
  • (16/25)λo
  • (20/λo
  • (27/λo
  • (25/λo
In the nuclear reaction 6C11 → 5B11 + β+ + X, what does X stands for?
  • An electron
  • A proton
  • A neutron
  • A neutrino
In the following nuclear reaction 6C11 + 5B11 + β+ + X, what does X stands for
  • A neutron
  • A neutrino
  • An electron
  • A proton
Two radioactive materials X1 and X 2 have decay constants 10λ and λ respectively. If initially, they have the same number of nuclei, then the ratio of the number of nuclei of X1 to that of X2 will be 1/e after a time

  • Physics-Atoms and Nuclei-62677.png
  • 2)
    Physics-Atoms and Nuclei-62678.png

  • Physics-Atoms and Nuclei-62679.png

  • Physics-Atoms and Nuclei-62680.png
Imagine an atom made up of proton and a hypothetical particle of double the mass of electron, but having the same charge as that of electron. Apply the Bohr atom model and consider all possible transitions of this hypothetical particle to the first excited level. The longest wavelength photon that will be emitted has wavelength constant R for hydrogen atom) equal to

  • Physics-Atoms and Nuclei-62682.png
  • 2)
    Physics-Atoms and Nuclei-62683.png

  • Physics-Atoms and Nuclei-62684.png

  • Physics-Atoms and Nuclei-62685.png
The transition from the state n = 4 to n = 3 in a hydrogen-like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition
  • 2 → 1
  • 3 → 2
  • 4 → 2
  • 5 → 4
The electron emitted in beta radiation originates from
  • inner orbits of atoms
  • free electrons existing in nuclei
  • decay of a neutron in a nucleus
  • photon escaping from the nucleus
An isobar is produced in
  • β-emission
  • α-emission
  • proton emission
  • deutron emission

Physics-Atoms and Nuclei-62687.png
  • 92, 236
  • 88, 230
  • 90, 234
  • 91, 234
Two deutrons each of mass m fuse to form helium resulting in release of energy E. The mass of helium formed is
  • m + E/c2
  • 2m + E/c2
  • E/mc2
  • 2m – E/c2
Wavelength in a spectrum is inversely proportional to
  • difference in energy levels
  • velocity of electrons
  • number of electrons
  • none of these
A nucleus with Z = 92 emits the following in a sequence: α, β–, β–, α, α, α, α, α, β–, β–, α, β+, β+ and α.
The Z of the resulting nucleus is
  • 76
  • 78
  • 82
  • 74
Which of the following cannot be emitted by radioactive substances during their decay?
  • Proton
  • Helium nucleus
  • Electron
  • Neutrino
Which of the following atoms has the lowest ionization potential?
  • 7N14
  • 55Cs133
  • 18Ar40
  • 8O16
The electric potential between a proton and an electron is given by V = V0 (r/r0), where r0 is a constant. Assuming Bohr’s model to be applicable, write variation of rn with n, n being the principal quantum number?
  • rn ∝ n
  • 2)
    Physics-Atoms and Nuclei-62691.png
  • rn ∝ n2

  • Physics-Atoms and Nuclei-62692.png
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