Question 5
The half-life of iodine-131 is 8 days. The amount of a 100 gram
sample of the isotope left d days after being introduced is
I = 100 (½)^d/8
What is the percent change per day?

A. 8.3% decrease per day
B. 91.7% decrease per day
C. 50% decrease per day
D. 99.6% decrease per day​