Strontium-90 is produced in nuclear explosions.It can replace calcium in the bone.The half-life of ⁹⁰Sr is 27.7 years.If the activity of ⁹⁰Sr in the bones of an exposed person were 90 disintegrations per second,how long would it take the activity of ⁹⁰Sr to decrease to 8.1 disintegrations per second?

Question

Quizplus · Accepted Answer

Explanation:The activity of a radioactive substance decreases exponentially with time. The half-life of a substance is the time it takes for the activity to decrease by half. The activity of ⁹⁰Sr in the bones of an exposed person is 90 disintegrations per second. The half-life of ⁹⁰Sr is 27.7 years. So, it will take 27.7 years for the activity to decrease to 45 disintegrations per second. It will take another 27.7 years for the activity to decrease to 22.5 disintegrations per second. And it will take another 27.7 years for the activity to decrease to 11.25 disintegrations per second. So, it will take a total of 27.7 * 3 = 83.1 years for the activity to decrease to 8.1 disintegrations per second.

Strontium-90 Is Produced in Nuclear Explosions