If a radioactive element has a half-life of 10,000 years,what fraction of it is left in a rock after 40,000 years?
A) One-half
B) One-fourth
C) One-eighth
D) One-sixteenth

Question

Quizplus · Accepted Answer

After the first half-life, half of the radioactive element would remain. Therefore, after 10,000 years, only half of the original amount would remain. After another 10,000 years (20,000 in total), only one-fourth (half of a half) would remain. After 30,000 years, only one-eighth (half of one-fourth) would remain. After 40,000 years, only one-sixteenth (half of one-eighth) would remain. Therefore, the fraction of the radioactive element left after 40,000 years is 1/16 or one-sixteenth.

If a Radioactive Element Has a Half-Life of 10,000 Years,what