CBSE  /  Class 12  /  Physics  /  Nuclei
  • 1. 
    How many electrons are contained in \(_{92}^{238}\)U nucleus?

  • 92
  • 146
  • 238
  • 0
  • 2. 
    Chadwick was awarded the Nobel prize in Physics in 1935 for his discovery of:

  • electron
  • proton
  • neutron
  • None of these
  • 3. 
    The density of a nucleus is of the order of:

  • 1015 kg m-3
  • 1018 kg m-3
  • 1017 kg m-3
  • 1016 kg m-3
  • 4. 
    When the mass of a sample of a radioactive substance decreases, the mean life of the sample:

  • increases
  • decreases
  • remain unchanged
  • first decreases then increases
  • 5. 
    Alpha particle emitted from a radioactive material are:

  • Helium nuclei
  • Hydrogen nuclei
  • Lithium nuclei
  • None of the above
  • 6. 
    The half life of a radioactive decay is n times its mean life, n is equal to:

  • 0.6930
  • 0.0693
  • \(\frac{1}{0.6930}\)
  • 0.3070
  • 7. 
    Rutherford is the unit of:

  • radioactivity
  • energy
  • photoelectric current
  • magnetic field
  • 8. 
    According to Yukawa's theory of nuclear forces, the origin of nuclear force between nucleons is due to the exchange of

  • mesons
  • photons
  • electrons
  • positrons
  • 9. 
    An electron and a positron each having a mass equivalent to 0.53 MeV annihilate each other and produce a photon. The minimum energy of the photon is.

  • 0.53 MeV
  • 1.06 MeV
  • 2.12 MeV
  • zero
  • 10. 
    The wavelength of y-rays is of the order of:

  • 10-8 m
  • 10-5 m
  • 10-11 m
  • 10-22 m
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