chemistry
posted by Shay .
It takes 1 hour and 17 min. for a 1.000g sample of a certain isotope to decay to 0.121g. What is the halflife of this isotope? plssss helpp

ln(No/N) = kt.
No = 1.000
N = 0.121
t = 67 min
solve for k, then
k = 0.693/t_{1/2}
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