A 77,4-mg supply of iodine- 131, used in hospitals in the treatment of hyperthyroidion, was stored for 40.11 days (d). IF the half-life of lodine- 181 is 8.021 days, how many mg remain? Be sure your answer has the correct number of significant figures.

Answer 1

Using the formula for radioactive decay:

Remaining amount = Initial amount * (1/2)^(t/half-life)

Remaining amount = 77.4 mg * (1/2)^(40.11 days / 8.021 days)

Remaining amount = 77.4 mg * (1/2)^5

Remaining amount = 77.4 mg * 1/32

Remaining amount = 2.41875 mg

Therefore, approximately 2.42 mg of iodine-131 remain after 40.11 days.