Question

select the correct answer.
the graph models the time, t, in minutes, required for a sample of the radioactive isotope francium - 223 to decay to a proportion, p, of its original mass.
approximately how long does it take a sample of francium - 223 to decay by 50%?
a. 20 minutes
b. 100 minutes
c. 40 minutes
d. 80 minutes

Explanation:

Step1: Understand the decay proportion

When the sample decays by 50%, the remaining proportion \(p = 1 - 0.5=0.5\).

Step2: Locate \(p = 0.5\) on the graph

On the given graph, find the value of \(t\) (time - axis) corresponding to \(p = 0.5\). By visual inspection of the graph, when \(p = 0.5\), the value of \(t\) is approximately 40 minutes.

Answer:

C. 40 minutes