if 10 mg of iodine 131 is given to a patient, how much is left after 24 days? the half - life of iodine…

Explanation:

Step1: Calculate number of half - lives

The half - life of iodine - 131 is 8 days and the time elapsed is 24 days. The number of half - lives $n=\frac{24}{8}=3$.

Step2: Use decay formula

The initial amount of iodine - 131 is $A_0 = 10$ mg. The formula for radioactive decay is $A=A_0\times(\frac{1}{2})^n$. Substituting $A_0 = 10$ mg and $n = 3$ into the formula, we get $A = 10\times(\frac{1}{2})^3$.

Step3: Calculate final amount

$A=10\times\frac{1}{8}=1.25$ mg.

Answer:

C. 1.25mg