Question

After 3 days a sample of radon-222 has decayed to 58% of its original amount.

(a) What is the half-life of radon-222? (Round your answer to two decimal places.)

b) How long will it take the sample to decay to 10% of its original amount? (Round your answer to two decimal places.)

Answer 1

The half-life of the radioactive substance can be determined through teh equation ln 2 = k (t 1/2) where k is equal to ln (1/(1-0.58)) / 3. Hence t 1/2 is equal to 2.40 days. To decay to 10% of the original amount, ln (1/0.90) / ( ln2) / 2.40, time is equal to 0.37 days.