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(a) do not change for any type of radioactivity.
(b) change for α and β radioactivity but not for γ-radioactivity.
(c) change for α-radioactivity but not for others.
(d) change for β-radioactivity but not for others.
9. Mx and My denote the atomic masses of the parent and the daughter nuclei respectively in a
+
–
radioactive decay. The Q-value for a β decay is Q1 and that for a β decay is Q2 If me denotes the
mass of an electron, then which of the following statements is correct? [NCERT Exemplar]

10. Samples of two radioactive nuclides A and B are taken λA and λB are the disintegration constants
of A and B respectively. In which of the following cases, the two samples can simultaneously have
the same decay rate at any time?
(a) Initial rate of decay of A is twice the » initial rate of decay of B and λA = λB.
(b) Initial rate of decay of A is less than the initial rate of decay of B and λA < λB.
(c) Initial rate of decay of B is twice the initial rate of decay of A and λA > λB.
(d) Initial rate of decay of B is same as the rate of decay of A at t = 2h and λB = λA.