A certain radioactive sample contains 2.4 $\times$ 10 3 nuclides at a certain time (t = 0);3.0 h later the sample contains 6.0 $\times$ 10 2 nuclides.
-For this sample the ratio of the decay rates at t = 0 to t = 3.0 h is:
A)1.0
B)8.0
C)4.0
D)16
E)none of these

Question

Quizplus · Accepted Answer

The decay rate of a radioactive sample is directly proportional to the number of nuclides present. Initially, there are $2.4 \times 10^{13}$ nuclides, and after 3 hours, there are $6.0 \times 10^{12}$ nuclides. The ratio of the initial number of nuclides to the number present after 3 hours is $\frac{2.4 \times 10^{13}}{6.0 \times 10^{12}} = 4$. Therefore, the ratio of the decay rates (initial rate to rate after 3 hours) is also 4.

A Certain Radioactive Sample Contains 2 ×\times× 103 Nuclides at a Certain Time (T = 0);3

A Certain Radioactive Sample Contains 2 $\times$ 10³ Nuclides at a Certain Time (T = 0);3