Question

what fraction of a radioactive sample has decayed after two half lives

Answer 1

Answer:

Well, 3/4th of the original isotope has decayed.

Explanation:

After 1 half-life, clearly HALF of the original isotope remains.

And after TWO half-lives, a

4

A

0

remains.

Fraction decayed = A

0

−

4

A

0

i.e. 3/4 of the original mass has decayed.