## Chemistry: The Molecular Science (5th Edition)

Number of half-lives underwent= $\frac{335\,h}{67.0\,h}=5$ There are exactly five half-lives. This means that the initial quantity is reduced by half five times. Amount of sample left= $1.000\,mg\times\frac{1}{2}\times\frac{1}{2}\times\frac{1}{2}\times\frac{1}{2}\times\frac{1}{2}$ $=1.000\,mg\times\frac{1}{32}=0.03125\,mg$