Question

Cobalt 60 has a half-life of about 5 years.

How many grams of 300 g sample will remain after 20 years?

1. 0.0625 g
2. 9.375 g
3. 18.75 g
4. 37.5 g

Answer 1

3. 18.75

Explanation:

took the test and got it correct

Answer 2

after 5 years ...150g
after 10 years..75 g
after 15 years...37,5
after 20 years...18,75 g