_{An isotope of Tc having a half-life of 6.0 h is used in bone scans.If a certain amo}_{unt of this Tc is injected into the body,how long does it take for its initial decay rate to decrease BY 99%?} A) _{0.060 h} B) _{3.3 h} C) _{33 h} D) _{40 h} E) _{slightly more than a month}

Question

Quizplus · Accepted Answer

To decrease the decay rate by 99%, only 1% of the original amount should remain. This corresponds to 6.64 half-lives (since 0.5^6.64 ≈ 0.01). Therefore, the time taken is 6.64 * 6.0 h = 39.84 h, which is approximately 40 h.

An Isotope of Tc Having a Half-Life of 6

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