Iodine-131 has a half-life of 8.1 days and is used as a tracer for the thyroid gland. If a patient drinks a sodium iodide (NaI) solution containing iodine-131 on a Tuesday, how many days will it take for the concentration of iodine-131 to drop to 5.0% of its initial concentration?

Question

Quizplus · Accepted Answer

To find the time it takes for the concentration to drop to 5.0%, we use the half-life formula: $ N(t) = N_0 \times (0.5)^{t/T} $, where $ N(t) $ is the final concentration, $ N_0 $ is the initial concentration, $ t $ is the time, and $ T $ is the half-life. Solving $ 0.05 = (0.5)^{t/8.1} $ gives $ t \approx 35 $ days.

Iodine-131 Has a Half-Life of 8