JEE Questions for Physics Atoms And Nuclei Quiz 17 - MCQExams.com

Energy of an electron in an excited hydrogen atom is –3.4 eV. Its angular momentum will be
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    Physics-Atoms and Nuclei-63333.png

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The ratio of speed of an electron in ground state in Bohr\'s first orbit of hydrogen atom to velocity of light in air is

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    Physics-Atoms and Nuclei-63338.png

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The de-Broglie wavelength of an electron in the first Bohr orbit is
  • Equal to one fourth the circumference of the first orbit
  • Equal to half the circumference of the first orbit
  • Equal to twice the circumference of the first orbit
  • Equal to the circumference of the first orbit
Energy of an electron in nth orbit of hydrogen atom is
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    Physics-Atoms and Nuclei-63344.png

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The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy ?
Physics-Atoms and Nuclei-63347.png
  • I
  • II
  • III
  • IV
As the electron in Bohr orbit of Hydrogen atom passes from state n = 2 to n = 1, the kinetic energy K and potential energy U change as
  • K two- fold, U four-fold
  • K four-fold, U two-fold
  • K four-fold, U also four-fold
  • K two-fold, U also two-fold
Bohr\'s atom model assumes
  • The nucleus is of infinite mass and is at rest
  • Electrons in a quantized orbit will not radiate energy
  • Mass of electron remains constant
  • All the above conditions
In Raman effect, Stoke\'s lines are spectral lines having
  • Frequency greater than that of the original line
  • Wavelength equal to that of the original line
  • Wavelength less than that of the original line
  • Wavelength greater than that of the original line
Two protons are kept at a separation of 40 Å. Fn is the nuclear force and Fe is the electrostatic force between them. Then
  • Fn << Fe
  • Fn ≈ Fe
  • Fn >> Fe
  • Fn = Fe
Which of the following transition in Balmer series for hydrogen atom will have longest wavelength?
  • n = 2 to n = 1
  • n = 6 to n = 1
  • n = 3 to n = 2
  • n = 6 to n = 2
v1 is the frequency of the series limit of Lyman series, v2 is the frequency of the first line of Lyman series and v3 is the frequency of the series limit of the Balmer series. Then

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    Physics-Atoms and Nuclei-63353.png

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Two energy levels of an electron in an atom are separated by 2.3 eV. The frequency of radiation emitted when the electrons goes from higher to the lower level is
  • 6.95 × 1014 Hz
  • 3.68 × 1015 Hz
  • 5.6 × 1014 Hz
  • 9.11 × 1015 Hz
A diatomic molecule is made of two masses m1 and m2 which are separated by a distance r. If we calculate its rotational energy by applying Bohr\'s rule of angular momentum quantization, its energy will be given by (n is an integer)

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    Physics-Atoms and Nuclei-63359.png

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Which of the following particles are constituents of the nucleus?
  • Protons and electrons
  • Protons and neutrons
  • Neutrons and electrons
  • Neutrons and positrons
The binding energies per nucleon for a deuteron and an α-particle are x1 and x2 respectively. What will be the energy Q released in the reaction
1H2 + 1H2 → 2He4 + Q
  • 4(x1 + x2)
  • 4(x2 – x1)
  • 2(x1 + x2)
  • 2(x2 – x1)
Nucleus of an atom whose atomic mass is 24 consists of
  • 11 electrons, 11 protons and 13 neutrons
  • 11 electrons, 13 protons and 11 neutrons
  • 11 protons and 13 neutrons
  • 11 protons and 13 electrons
Isotopes are atoms having
  • Same number of protons but different number of neutrons
  • Same number of neutrons but different number of protons
  • Same number of protons and neutrons
  • None of the above
The mass of an α-particle is
  • Less than the sum of masses of two protons and two neutrons
  • Equal to mass of four protons
  • Equal to mass of four neutrons
  • Equal to sum of masses of two protons and two neutrons
A nucleus ruptures into two nuclear parts which have their velocity ratio equal to 2 : 1. What will be the ratio of their nuclear size (nuclear radius)
  • 21/3 : 1
  • 1: 21/3
  • 31/3 : 1
  • 1 : 31/3
Which of the following isotopes is normally fissionable?
  • 92U238
  • 93NP239
  • 92U235
  • 2He4
When a 4Be9 atom is bombarded with α-particles, one of the products of nuclear transmutation is 6C12. The other is
  • –1e0
  • 1H1
  • 1D2
  • 0n1
A radioactive sample S1 having the activity A1 has twice the number of nuclei as another sample S2 of activity A2. If A2 = 2A1, then the ratio of half life of S1 to the life of S2 is
  • 4
  • 2
  • 0.25
  • 0.75
During the 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
A gamma ray photon creates an electron-positron pair. If the rest mass energy of an electron is 0.5 MeV and the total K.E. of the electron-positron pair is 0.78 MeV, then the energy of the gamma ray photon must be
  • 0.78 MeV
  • 1.78 MeV
  • 1.28 MeV
  • 0.28 MeV
In a fission process, nucleus A divides onto two nuclei B and C, their binding energies being Ea, Eb and Ec, respectively. Then
  • Eb + Ec < Ea
  • Eb + Ec = Ea
  • Eb + Ec > Ea
  • Eb + Ec = Ea
Complete the equation for the following fission process
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    Physics-Atoms and Nuclei-63372.png

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The example of nuclear fusion is
  • Formation of barium and krypton from uranium
  • Formation of helium from hydrogen
  • Formation of plutonium 235 from uranium 235
  • Formation of water from hydrogen and oxygen
Energy in the sun is generated mainly by
  • Fusion of radioactive material
  • Fission of helium atoms
  • Chemical reaction
  • Fusion of hydrogen atoms
When a slow neutron goes sufficiently close to a U235 nucleus, then the process that takes place is
  • Fission of U235
  • Fusion of neutron
  • Fusion of U235
  • First (then (2)
Which of the following is a fusion reaction ?

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  • 2)
    Physics-Atoms and Nuclei-63378.png

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  • None of the above
Energy released in fusion of 1 kg of deuterium nuclei
  • 8 × 1013 J
  • 6 × 1027 J
  • 2 × 107 kwh
  • 8 × 1023 MeV
Which of the following is true for a sample of isotope containing U235 and U238?
  • Number of neutrons are same in both
  • Number of protons, electrons and neutrons are same in both
  • Contain same number of protons and electrons but U238 contains 3 more neutrons than U235
  • U238 contains 3 less neutrons than U235
During the β - decay
  • An atomic electron is ejected
  • An electron, already present within the nucleus, is ejected
  • A proton in the nucleus decays emitting an electron
  • A neutron in the nucleus decay emitting an electron
The energy liberated on complete fission of 1 kg of 92U235 is (Assume 200 MeV energy is liberated on fission of 1 nucleus)
  • 8.2 × 1010 J
  • 8.2 × 109 J
  • 8.2 × 1013 J
  • 8.2 × 1016 J
Which one of the following statements about uranium is correct?
  • 235U is fissionable by thermal neutrons
  • Fast neutrons trigger the fission process in 235U
  • 238U breaks up into fragments when bombarded by slow neutrons
  • 235U is an unstable isotope and undergoes spontaneous fission
The nuclear reaction 2H + 2H → 4He (mass of deuteron = 2.0141 amu and mass of He = 4.0024 amu) is
  • Fusion reaction releasing 24 MeV energy
  • Fusion reaction absorbing 24 MeV energy
  • Fission reaction releasing 0.0258 MeV energy
  • Fission reaction absorbing 0.0258 MeV energy
Two lithium nuclei in a lithium vapor at room temperature do not combine to form a carbon nucleus because
  • Carbon nucleus is an unstable particle
  • It is not energetically favorable
  • Nuclei do not come very close due to coulombic repulsion
  • Lithium nucleus is more tightly bound than a carbon nucleus
Heavy water is
  • Water at 4° C
  • Compound of deuterium and oxygen
  • Compound of heavy oxygen and heavy hydrogen
  • Water, in which soap does not lather
If M is the atomic mass and A is the mass number, packing fraction is given by

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1 atomic mass unit is equal to

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The nucleus 92U234 splits exactly in half in a fission reaction in which two neutrons are released. The resultant nuclei are
  • 46Pd116
  • 4Rh117
  • 45Rh116
  • 46Pd117

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  • 4v/206
  • 4v/214
  • v/206
  • v/214
The curve of binding energy per nucleon as a function of atomic mass number has a sharp peak for helium nucleus. The implies that helium
  • Can easily be broken up
  • Is very stable
  • Can be used as fissionable material
  • Is radioactive
When U235 is bombarded with one neutron, the fission occurs and the products are three neutrons, 36Kr94 and
  • 52I142
  • 56Ba139
  • 58Ce139
  • 54Xe139
If r1 and r2 are the radii of the atomic nuclei of mass numbers 64 and 125 respectively, then the ratio (r1 / r2) is

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    Physics-Atoms and Nuclei-63397.png

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The subatomic particles proton and neutron fall under the group of
  • Mesons
  • Photons
  • Leptons
  • Baryons
Sun energy is due to
  • Fission of hydrogen
  • Fusion of hydrogen
  • Both fission and fusion
  • Neither fusion nor fission
Assume that a neutron breaks into a proton and an electron. The energy released during this process is (mass of neutron = 1.6725 × 10–27 kg, mass of proton = 1.6725 × 10–27 kg, mass of electron = 9 × 10–31 kg)
  • 0.73 MeV
  • 7.10 MeV
  • 6.30 MeV
  • 5.4 MeV
The half-life period of radium is 1600 years. Its average life time will be
  • 3200 years
  • 4800 years
  • 2319 years
  • 4217 years
If λ is decay constant and N the number of radioactive nuclei of an element, the decay rate (R) of that element is
  • λN2
  • λN
  • λ/N
  • λ2N
0:0:1


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