Question

Question: Carbon-11 has a half-life of about 20 minutes. If we start with 200 grams, how

much will be left after 3 hours?

A. 25 grams
B. 2.5 grams
C. 0.39 grams
D. 0.039 grams

Answer 1

C). 0.39 grams

Explanation:

First find how many half-lifes are in 3 hours:

3 hours ÷ 20 minutes = 9 half-lifes

Find the total left:

0.5^9*200 ≈ 0.39