Question

HALF LIFE The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning,

how many grams would be left after 7.2 minutes has elapsed?

A: 50.0 grams
B: 100.0 grams
C: 8.5 grams
D: 12.5 grams

Answer 1

7.2 / 2.4 = 3 half-lives

(1/2)3 = 0.125 (the amount remaining after 3 half-lives)

100.0 g x 0.125 = 12.5 g remaining

Hope this Helped! :)