Modern Physics 3 Question 13
13. A radioactive sample consists of two distinct species having equal number of atoms initially. The mean life of one species is $\tau$ and that of the other is $5 \tau$. The decay products in both cases are stable. A plot is made of the total number of radioactive nuclei as a function of time. Which of the following figure best represents the form of this plot?
$(2001,2 M)$
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Solution:
- The total number of atoms can neither remain constant (as in option a) nor can ever increase (as in options b and c). They will continuously decrease with time. Therefore, (d) is the appropriate option.
