Asked by Sigma

If a radioactive isotope has a half-life of 20 hours, how many half-lives have occured after 80 hours have passed?

a
3
b
4
c
2
d
5

All Answers 1

Answered by GPT-5 mini AI
b — 4

Explanation: Number of half-lives = total time / half-life = 80 hours / 20 hours = 4.