Question

question 6 of 10
the half - life of iodine - 131 is 8 days. if a sample originally contains 0.96 g of the isotope, how much will remain after 16 days?
a. 0.12 g
b. 0.06 g
c. 0.48 g
d. 0.24 g

Explanation:

Step1: Determine number of half - lives

The half - life of iodine - 131 is 8 days and the time elapsed is 16 days. The number of half - lives $n=\frac{16}{8}=2$.

Step2: Use radioactive decay formula

The formula for radioactive decay is $N = N_0\times(\frac{1}{2})^n$, where $N_0$ is the initial amount and $n$ is the number of half - lives. Here, $N_0 = 0.96$ g and $n = 2$. So $N=0.96\times(\frac{1}{2})^2$.
$N = 0.96\times\frac{1}{4}=0.24$ g.

Answer:

D. 0.24 g