_{An isotope of Tc having a half-life of 6.0 h is used in bone scans. If a certain amount of this Tc is injected into the body, how long does it take for its initial decay rate to decrease BY 99%?}

Question

Quizplus · Accepted Answer

To decrease by 99%, only 1% remains. Using the formula $ t = n \times t_{1/2} \times \log(1/\text{remaining fraction})/\log(2) $, where $ n $ is the number of half-lives, we find $ t \approx 40 $ hours.

An Isotope of Tc Having a Half-Life of 6

_{An Isotope of Tc Having a Half-Life of 6}