Answer:
0.9375 grams
Explanation:
As we know half life is the time period in which quantity of a substance reduces to half of its original value.
The formula to calculate amount of substance left after n half life is [tex]x/2^n[/tex]
where x is the amount of original substance
n is the no of half life.
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Given
No. of half lives = 4
amount of original substance = 15 gram
thus,
n = 4
x = 15 grams
amount of radioisotope left after 4 half life = [tex]x/2^n = 15 \ gram/2^4 = 15 \ grams / 16 = 0.9375 \ grams\\[/tex]
Thus, only 0.9375 grams of radioisotope are left after 4 half lives.
