The partly existence of 131I is 8 days. If a medical treatment involves a dose of 400 mg of 131I, how much of the?
200 mg
100 mg
50 mg
25 mg
Answer:
1/2 is "gone" after 8 days, another 1/4 (of the original) is gone after 16 days, another 1/8 is gone after 24 days, and another 1/16 is gone after 32 days. Add the fractions, and you get 15/16. So solitary 1/16 of the original textile is still active, and that would be 25 mg.
25mg. Four half-lifes will end in a (2^-4) reduction, or a 1/16th slimming down (2*2*2*2=16).
Are you just posting homework question because you posted like 3 multiple choice question already.