Question

25 grams of radon-222 remains after 15.28 days. How much radon was in the original sample? Write an equation for the decay of radon-222.

Answer 1

half-life = 3.8 days

total time of decay = 15.2 days

initial amount = 100. g

number of half-lives past: 15.2/3.8 = 4 half-lives

4 half-lives = 1/16 remains

100. g x 1/16 = 6.25 g