An original sample of the radioisotope fluorine-21 had a mass of 80.0 milligrams. Only 20.0 milligrams of this original sample remain unchanged after 8.32 seconds. What is the half-life of fluorine-21?

(1) 1.04 s (3) 4.16 s

(2) 2.08 s (4) 8.32 s

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23 November, 03:36

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Mira Pugh · Answer 1

1/2 of 80 mg = 40 mg (1 half life), 20 mg means 2 half lives have passed in 8.32 seconds SO the half life is 8.32/2 = 4.16 s

An original sample of the radioisotope fluorine-21 had a mass of 80.0 milligrams. Only 20.0 milligrams of this original sample remain unchanged after 8.32 seconds. What is the half-life of fluorine-21?(1) 1.04 s (3) 4.16 s(2) 2.08 s (4) 8.32 s