A radioactive substance has a half-life of 20 hours. What fraction of the original radioactive nuclide will remain after 80 hours?
A
1/32
B
\(\frac{1}{16}\)
C
\(\frac{1}{8}\)
D
\(\frac{1}{4}\)
E
\(\frac{1}{2}\)
Verified Correct Answer: B.
Physical Principles & Numerical Solution
Fraction remaining = (\(\frac{1}{2}\))\(^{\frac{t}{T_{\frac{1}{2}}}}\)
BUT \(\frac{t}{T_{\frac{1}{2}}}\) = \(\frac{80}{20}\) = 4
Fraction remaining = (\(\frac{1}{2})^4\) = \(\frac{1}{16}\)
Source: Myschool Past Questions Archive (Record #25047)