Questions: A medical technician is working with the four samples of radionuclides listed in the table below. Initially, each sample contains 19.00 μmol of the radionuclide. First, order the samples by decreasing initial radioactivity. Then calculate how long it will take for the amount of radionuclide in each sample to decrease to 1 / 4 of the initial amount. sample radionuclide half-life initial radioactivity time for amount of radionuclide to decrease to 1 / 4 of initial amount --- --- --- --- --- A 149 To 65 4 hours 2v hours B 30^62 Zn 9.0 hours 3 ~ hours c 31^68 Ga 68.0 minutes 1 (highest) v minutes D 79^198 Au 3 days 4 (lowest) days

Transcript text: A medical technician is working with the four samples of radionuclides listed in the table below. Initially, each sample contains $19.00 \mu \mathrm{~mol}$ of the radionuclide. First, order the samples by decreasing initial radioactivity. Then calculate how long it will take for the amount of radionuclide in each sample to decrease to $1 / 4$ of the initial amount. \begin{tabular}{|c|c|c|c|c|} \hline \multirow[t]{2}{*}{sample} & \multicolumn{2}{|r|}{radionuclide} & \multirow[t]{2}{*}{initial radioactivity} & \multirow[t]{2}{*}{time for amount of radionuclide to decrease to $1 / 4$ of initial amount} \\ \hline & symbol & half-life & & \\ \hline A & \begin{tabular}{l} \[ 149 \] \\ To \[ 65 \] \end{tabular} & 4. hours & $2 v$ & $\square$ hours \\ \hline B & \[ { }_{30}^{62} \mathrm{Zn} \] & 9.0 hours & $3 \sim$ & $\square$ hours \\ \hline c & \[ { }_{31}^{68} \mathrm{Ga} \] & 68.0 minutes & 1 (highest) v & $\square$ minutes \\ \hline D & \[ { }_{79}^{198} \mathrm{Au} \] & 3. days & 4 (lowest) & $\square$ days \\ \hline \end{tabular}