Atoms

15 Questions

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Atoms

Time : 30 Minute


Questions and Answers
  • 1. 
    The energy equivalent to one atomic mass unit is:
    • A. 
    • B. 
    • C. 

      9.23 Mev

    • D. 

      931 MeV

  • 2. 
    The ratio of radii of orbits corresponding to first and second excited states of hydrogen atom is:
    • A. 

      1 : 3

    • B. 

      1 : 2

    • C. 

      2: 3

    • D. 

      4 : 9

  • 3. 
    The series of hydrogen spectrum which lies in visible region is:
    • A. 

      Lymann series

    • B. 

      Balmer series

    • C. 

      Paschen series

    • D. 

      None of the above

  • 4. 
    The order of velocity of electron in ground sate of hydrogen is:
    • A. 

      10 m/s

    • B. 

      106 m/s

    • C. 

      10-6 m/s

    • D. 

      108 m/s

  • 5. 
    The diameter of the first orbit of the hydrogen atom is of the order of:
    • A. 

      0.5 Ǻ

    • B. 

      1 Ǻ

    • C. 

      2 Ǻ

    • D. 

      4 Ǻ

  • 6. 
    • A. 

      Of the electrons not being subject to a central force

    • B. 

      Of the electrons colliding with each other

    • C. 

      Of screening effect

    • D. 

      The force between the nucleus and an electron will no longer be given by Coulomb’s Law

  • 7. 
    Two H atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced is:
    • A. 

      10.20 eV

    • B. 

      20.40 eV

    • C. 

      13.6 eV

    • D. 

      27.2 eV

  • 8. 
    Hydrogen atom is excited from ground sate to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be:
    • A. 

      2

    • B. 

      3

    • C. 

      5

    • D. 

      6

  • 9. 
    Taking the Bohr radius as ao = 53pm, the radius of Li2+ ion in its ground state, on the basis of Bohr’s model, will be about:
    • A. 

      53 pm

    • B. 

      27 pm

    • C. 

      18 pm

    • D. 

      13 pm

  • 10. 
    Which of the following transitions in a hydrogen atom emit a photon of highest frequency?
    • A. 

      N = 2 to n = 6

    • B. 

      N = 6 to n = 2

    • C. 

      N = 1 to n = 2

    • D. 

      N = 2 to n = 1

  • 11. 
    In a Rutherford scattering experiment, when a projectile of charge Q and mass M approaches a target nucleus of charge q and mass m, the distance of closest approach is r. The energy of the projectile is:
    • A. 

      Directly proportional to mass M

    • B. 

      Directly proportional to

    • C. 

      Directly proportional to Qq

    • D. 

      Directly proportional to Q

  • 12. 
    The positron was discovered by:
    • A. 

      Chadwick

    • B. 

      Bohr

    • C. 

      Maxwell

    • D. 

      Anderson

  • 13. 
    Energy of electron in t6hye 1st orbit of H-atom is:
    • A. 

      –13.6 MeV

    • B. 

      –13.6 eV

    • C. 

      –13.6 J

    • D. 

      13.6 J

  • 14. 
    With increasing quantum number, the energy difference between adjacent energy levels in atoms:
    • A. 

      Increases

    • B. 

      Decreases

    • C. 

      Remains constant

    • D. 

      First increases then decreases

  • 15. 
    . Let there be a system of energy levels of a certain atom. When the system moves from 2E level to E, a photon of wavelength λ is emitted. The wavelength of photon produced during its transition from level to E is:
    • A. 
    • B. 
    • C. 
    • D.