A radioisotope has a half-life of 7.5 hours. How many half lives have occured after 67.5 hours?
a
7 half-lives
b
8 half-lives
c
9 half-lives
d
10 half-lives
c. 9 half-lives
To determine the number of half-lives that have occurred after 67.5 hours, we can divide the total time by the half-life.
67.5 hours / 7.5 hours (half-life) = 9 half-lives
Therefore, the correct answer is c) 9 half-lives.
To determine the number of half-lives that have occurred after a certain period of time, you need to divide the total time by the half-life duration.
In this case, the total time is given as 67.5 hours, and the half-life is 7.5 hours.
To find the number of half-lives:
67.5 hours รท 7.5 hours = 9
So, after 67.5 hours, a total of 9 half-lives have occurred.
Therefore, the correct answer is c) 9 half-lives.