Question

Radon-222 has a half life of 3.82 days. How much radon - 222 will remain after 11.46 days if you started with a 3.0 mg sample?

Answer 1

Hey there!

A half-life means after a certain amount of time, half of that substance will be gone/changed after that time.

There are 3 half lives in 11.46 days because 11.46 ÷ 3.82 = 3.

So, we divide the 3mg sample in half 3 times.

3 ÷ 2 = 1.5

1.5 ÷ 2 = 0.75

0.75 ÷ 2 = 0.375

There will be 0.375mg of radon-222 remaining after 11.46 days.

Hope this helps!