Modern Physics 3 Question 19

19. Masses of two isobars ${ } _{29} Cu^{64} and _{30} Zn^{64}$ are $63.9298 u$ and $63.9292 u$ respectively. It can be concluded from these data that

(1997C, 1M)

(a) both the isobars are stable

(b) $Zn^{64}$ is radioactive, decaying to $Cu^{64}$ through $\beta$-decay

(c) $Cu^{64}$ is radioactive, decaying to $Zn^{64}$ through $\gamma$-decay

(d) $Cu^{64}$ is radioactive, decaying to $Zn^{64}$ through $\beta$-decay

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Solution:

  1. In beta decay, atomic number increases by 1 whereas the mass number remains the same.

Therefore, following equation can be possible

$$ { } _{29}^{64} Cu \rightarrow{ } _{30}^{64} Zn+{ } _{-1} e^{0} $$



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