The half-life of iodine-125 is 60 days. About how much of a 144 gram sample will remain after 1 year?

60 x 5 = 300 days

So five half-lifes = 300 days

Starting amount = 500mg

Amount after 1st half-life = 250 mg

Amount after 2nd half-life = 125 mg

Amount after 3rd half-life = 62.5 mg

Amount after 4th half-life = 31.25 mg

Amount after 5th half-life = 15.625 mg

Hence after 300 days, the amount of iodine-125 will be 15.625 mg out of 500 mg.

Explanation:

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