Science chemistry

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It takes 1 hour and 17 min. for a 1.000gsample of a certain isotope to decay to 0.121g. What is the half-life of this isotope? plssss helpp

  • Science chemistry -

    if n is the number of half-lives

    (1/2)^n * 1.000 = 0.121

    (1/2)^n = 0.121/1.000

    n [log(1/2)] = log(0.121)

    n = [log(0.121)] / [log(1/2)]

    half life = [1h17m] / n

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