Strontium-90 is a dangerous isotope because strontium is chemically similar to calcium and is easily incorporated into bones. Sr-90 has a half-life of 28.1 years. If a person ingests 100 mg of Sr-90, identify the amount that is left in the person's body after 56.2 years.

Question

Quizplus · Accepted Answer

After 28.1 years, half of the initial 100 mg of Sr-90 will remain in the person's body, which is 50 mg. After another 28.1 years (56.2 years total), another half of the remaining 50 mg will decay, leaving 25 mg in the person's body. Therefore, the best choice is C, which represents the amount of Sr-90 left in the person's body after 56.2 years.

Strontium-90 Is a Dangerous Isotope Because Strontium Is Chemically Similar