Answer:
B. False
The true statement will be:
After three half-lives, one-eighth of an original radioactive parent isotope remains, and seven-eighth has decayed into daughter isotopes.
Explanation:
Half life means the time after which the amount of the given substance becomes half of its initial amount, by radiation.
Thus after each successive half life the material is halved or half of it is decayed, which leads to a general formula:
Remaining Amount = 1/2^n of parent isotope
where, n is the number of half lives passed. So, for three half-lives:
Remaining Amount = 1/2^3 of parent isotope
<u>Remaining Amount = 1/8 of parent isotope</u>
Thus, the decayed amount will be:
Decayed Amount = (1-1/8) of parent isotope
<u>Decayed Amount = 7/8 of parent isotope</u>
Thus, the given statement is <u>B.False</u>
