What percentage of a radioactive species would be found as daughter material after seven half–lives?
choices
a. 70%
b. 7%
c, 6.25%
d. 0.78%

The relation between number of half-lives and the amount of sample that remained is expressed as: (1/2)^n = x So, given is 7. To find x, we will change the equation with 7: (1/2)^n = x (1/2)^7 = x 0.5^7 = x 0.0078125 = x 0.0078125 x 100% = x x = 0.78125 Therefore, 0.78 % of a radioactive species would be created as daughter material after seven half-lives.

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