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  • 天同
    Lv 7
    7 years ago
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    16. The answer is option D.

    Statement (1) is wrong. Biological effect is due to difference in ionization power of the the two types of radiation.

    17. The answer is option D.

    20. Let m be the mass of a protron or neutron

    Mass of an alpha particle = 4m

    Mass of the residual nucleus = (50+50-4)m = 96m

    By conservation of momenum,

    (4m).(v1) = (96m).(v2)

    where v1 and v2 are the speeds of the alpha particle and residual nucleus respectively.

    hence, v2/v1 = 4/96 = 1/24

    Therefore, kinetic energy of alpha particle, K1 = (1/2).(4m)(v1)^2

    Kinetic energy of residual nucleus, K2 = (1/2).(96m)(v2)^2

    K2/K1 = [(1/2).(96m)(v2)^2]/[ (1/2).(4m)(v1)^2] = (96/4).(v2/v1)^2

    i.e. K2/K1 = (96/4).(1/24)^2 = 1:24

    None of the options is correct.

    21. The answer is option D.

    Emission of characteristic x-rays is due to change in energy levels of orbital electrons. Emission of gamma rays is due to change of energy levels of the nucleus from excited state to ground state.

    Emission of beta particle only involves change in atomic no., but not mass no.

    26. The answer is option C.

    Nuclear fission is not a spontaneous process. It needs to be triggered.

    28. The answer is option B.

    29. Masses of He and N = (4.0026 + 14.00307) u = 18.00567

    Total energy before reaction = (18.00567 x 931 + 5.3) MeV = 16769 MeV

    Masses of proton and O = (1.00728 + 16.99913) x 931 MeV = 16764 MeV

    Energy released = (16769 - 16764) MeV = 5 MeV

    Energy shared by the proton = 4.72 MeV

    The most likely answer is thus option C.

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