The half-life of an isotope of tritium is 4500 days. How many days will it take an amount of tritium to fall to a quarter of its initial mass?

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Answer 1 · 2018-04-29T07:23:39

9000 days.

Decay can be described by the following equation:

#M_0="initial mass"#

#n#=number of half lives

#M=M_0 times (1/2)^n#

#(1/4)=1 times (1/2)^n#

#(1/4)=(1^2/2^2)#

So #n=2#, which means 2 half-lives must have passed.

1 half-life is 4500 days, so it must take #2 times 4500=9000# days for the sample of tritium to decay to a quarter of its initial mass.