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Set 2 of 16 · Questions 31-60 of 453

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JEE Main Physics · Atoms · Set 2 (Q31-60)

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  1. 31.
    Radiation, with wavelength falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of . If the radius of the largest circular path followed by the electrons is , the work function of the metal is close to:
    1. (1)1.8 eV
    2. (2)0.8 eV
    3. (3)1.1 eV
    4. (4)1.4 eV
  2. 32.
    The energy of the ground electronic state of hydrogen atom is‐ 13.6 ne energy of the first excited state will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  3. 33.
    Mass numbers of two nuclei are in the ratio of 4 : 3. Their nuclear densities will be in the ratio of
    1. (1)4 : 3
    2. (2)
    3. (3)1 : 1
    4. (4)
  4. 34.
    A particle of mass ' ' and charge ' ' is accelerated by a potential difference of 50 V . Another particle B of mass 4 m and charge q is accelerated by a potential difference of 2500 V . The ratio of de-Broglie wavelengths is close to :
    1. (1)14.14
    2. (2)10.00
    3. (3)0.07
    4. (4)4.47
  5. 35.
    The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  6. 36.
    -particle scatters from a target material of atomic number 79. From the given data the estimated diameter of nuclei of the target material is (approximately) m. and electron charge
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  7. 37.
    If the momentum of electron is changed by , then the de Broglie wavelength associated with it changes by . The initial momentum of electron will be:
    1. (1)200 P
    2. (2)400 P
    3. (3)
    4. (4)100 P
  8. 38.
    In the Bohr model of a hydrogen atom, the centripetal force is furnished by the coulomb attraction between the proton and the electron. If is the radius of the ground state orbit, is the mass and is the charge on the electron and is the vacuum permittivity, the speed of the electron is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  9. 39.
    The energy of a hydrogen atom in the ground state is The energy of a ion in the first excited state will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  10. 40.
    An electron of mass m and magnitude of charge |e| initially at rest gets accelerated by a constant electric field . The rate of change of de-Broglie wavelength of this electron at time ignoring relativistic effects is:
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  11. 41.
    If an alpha particle with energy 7.7 MeV is bombarded on a thin gold foil, the closest distance from nucleus it can reach is m. (Atomic number of gold and in SI units)
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  12. 42.
    A radioactive nucleus can decay by two different processes. Half-life for the first process is 3.0 hours while it is 4.5 hours for the second process. The effective half- life of the nucleus will be:
    1. (1)3.75 hours
    2. (2)0.56 hours
    3. (3)0.26 hours
    4. (4)1.80 hours
  13. 43.
    The wavelength of the first line in Balmer series in the hydrogen spectrum is ' '. What is the wavelength of the second line in the same series?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  14. 44.
    Given below are two statements:
    Statement I: For all elements, greater the mass of the nucleus, greater is the binding energy per nucleon.
    Statement II: For all elements, nuclei with less binding energy per nucleon transforms to nuclei with greater binding energy per nucleon.
    In the light of the above statements, choose the correct answer from the options given below
    1. (1)Statement I is true but Statement II is false
    2. (2)Both Statement I and Statement II are true
    3. (3)Both Statement I and Statement II are false
    4. (4)Statement I is false but Statement II is true
  15. 45.
    The nuclei and can be described as
    1. (1)isotones
    2. (2)isobars
    3. (3)isotopes of carbon
    4. (4)isotopes of nitrogen
  16. 46.
    What is the half-life period of a radioactive material if its activity drops to 1/ of its initial value of 30 years?
    1. (1)9.5 years
    2. (2)8.5 years
    3. (3)7.5 years
    4. (4)10.5 years
  17. 47.
    The shortest wavelength in the Paschen series of the Hydrogen spectrum is Rydberg constant of hydrogen .
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  18. 48.
    A nucleus has mass number and radius . Another nucleus has mass number and radius . If then is:
    1. (1)8
    2. (2)0.5
    3. (3)2
    4. (4)1
  19. 49.
    The time period of revolution of electron in its ground state orbit in a hydrogen atom is . The frequency of revolution of the electron in its first excited state (in ) is:
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  20. 50.
    An electron makes a transition from orbit to the orbit of a hydrogen atom. What is the wavelength of the emitted radiations? constant)
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  21. 51.
    The ratio of wavelength for transition of electrons from orbit to orbit of Helium and Lithium is (Atomic number of Helium , Atomic number of Lithium
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  22. 52.
    is the frequency of the series limit of Lyman series, is the frequency of the first line of Lyman series and is the frequency of the series limit of the Balmer series. Then
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  23. 53.
    An electron revolving in Bohr orbit has magnetic moment . If , the value of is:
    1. (1)2
    2. (2)1
    3. (3)3
    4. (4)0
  24. 54.
    In an electron microscope, the resolution that can be achieved is of the order of the wavelength of electrons used. The resolve a width of , the minimum electron energy required is close to :
    1. (1)500 keV
    2. (2)25 keV
    3. (3)1 keV
    4. (4)100 keV
  25. 55.
    The frequency of revolution of the electron in Bohr's orbit varies with , the principal quantum number as
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  26. 56.
    Given below are two statements:
    Statement I: Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford's model.
    Statement II: An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford's model.
    In the light of the above statements, choose the most appropriate from the options given below.
    1. (1)Both statement I and statement II are false
    2. (2)Statement I is false but statement II is true
    3. (3)Statement I is true but statement II is false
    4. (4)Both statement I and statement II are true
  27. 57.
    A particle of mass moves in a circular orbit in a central potential field . If Bohr's quantization conditions are applied, radii of possible orbitals vary with , where is ______
  28. 58.
    The radius of fifth orbit of is_______x m. Take: radius of hydrogen atom = 0. 51 Å
  29. 59.
    The wavelength of an ray beam is . The mass of a fictitious particle having the same energy as that of the ray photons is . The value of is
  30. 60.
    A nucleus has mass number and volume . Another nucleus has mass number and volume . If relation between mass number is , then _______