Question

Carbon-10 has a half-life of about 19 seconds. How many half-lives does it undergo in 2 minutes and 32 seconds?

• A. 8 half-lives
• B. 7 half-lives
• C. 6 half-lives
• D. 5 half-lives
• E. 4 half-lives

Answer 1

Answer: (A)

8 half-lives

Total time is 2 minutes and 32 seconds, i.e., $2\times 60+32=152$ seconds.
The half life period is 19 seconds.
The number of half life periods $=\frac{152}{19}=8$.