Answer:
~ 20 half lives
Step-by-step explanation:
(1/2) ^n = 1/1,000,000 n = number of half-lives
LOG both sides to get
n LOG 1/2 = -6
n = -6/(LOG (1/2)) = 19.931 or approx 20 half lives
it would depend on which element u would be considering
as helium , oxygen , carbon ,sodium and other would be easier while plutonium , americium and other very radioactive elements would be harder
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