A radioactive sample initially contains N atoms. After three half-lives the number of atoms that have disintegrated is
- \(\frac{N}{8}\)
- \(\frac{3N}{8}\)
- \(\frac{5N}{8}\)
-
\(\frac{7N}{8}\)
The correct answer is: D
Explanation
N \(\to\) \(\frac{N}{2}\) \(\to\) \(\frac{N}{4}\) \(\to\) \(\frac{N}{8}\)
Number of atoms left = 1-1/8=\(\frac{7N}{8}\)