A radioactive sample initially contains N atoms. After three half-lives the number of atoms that have disintegrated is
A
\(\frac{N}{8}\)
B
\(\frac{3N}{8}\)
C
\(\frac{5N}{8}\)
D
\(\frac{7N}{8}\)
Verified Correct Answer: D.
Physical Principles & Numerical Solution
N \(\to\) \(\frac{N}{2}\) \(\to\) \(\frac{N}{4}\) \(\to\) \(\frac{N}{8}\)
Number of atoms left = 1-1/8=\(\frac{7N}{8}\)
Source: Myschool Past Questions Archive (Record #28482)