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if the isotope decays in 100 days and the half life is 25 days,then the isotope must have undergone 100/25 decays=4 decays.
therefore the 4th decay wil be [1/2] raised to power 4=1/16
this means that 1/16 of M=5 grams
hence M=16*5 grams=80 grams
Kevinsenzoochieng answered the question on July 5, 2019 at 14:00
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