Answer:
The reading of the Geiger counter, 22 minutes later = 29 counts per minute (cpm)
Explanation:
Half life is defined as the time taken for the amount ( or activity) of a substance to reduce to half its original value.
As stated in the question, the half life of Francium-233 is 22 minutes, [tex]t_{1/2} = 22 minutes[/tex]. This means that it takes 22 minutes for the activity of Francium-233 to reduce to half of its original value.
The original activity of Francium-233 = 58 counts per minute (cpm)
By the end of 22 minutes, the activity measured by the counter would have halved.
Activity of Francium-233 after 22 minutes = 58/2
Activity of Francium-233 after 22 minutes = 29 counts per minute (cpm)
