A sample of radon has an activity of 90,000 Bq. If the half-life of radon is 15 h, how long before the sample's activity is 5,625 Bq?

Question

Quizplus · Accepted Answer

The activity of a radioactive sample decreases exponentially with time, following the formula $A = A_0 \times (1/2)^{t/T}$, where $A$ is the final activity, $A_0$ is the initial activity, $t$ is the time elapsed, and $T$ is the half-life of the substance. To find the time when the activity decreases from 90,000 Bq to 5,625 Bq, we can set up the equation $5,625 = 90,000 \times (1/2)^{t/15}$. Solving for $t$, we find that $t = 60$ hours.

A Sample of Radon Has an Activity of 90,000 Bq