From the densities of the lines in the mass spectrum of krypton gas, the
following observations were made:
\bullet Somewhat more than \(50 \%\) of the atoms were krypton-84.
\(\bullet\) The numbers of krypton- 82 and krypton- 83 atoms were essentially
equal.
\(\bullet\) The number of krypton-86 atoms was 1.50 times as great as the number
of krypton- 82 atoms.
\(\bullet\) The number of krypton-80 atoms was \(19.6 \%\) of the number of
krypton- 82 atoms.
\(\bullet\) The number of krypton- 78 atoms was \(3.0 \%\) of the number of
krypton- 82 atoms. The masses of the isotopes are \(^{78} \mathrm{Kr}, 77.9204
\mathrm{u} \quad^{80} \mathrm{Kr}, 79.9164 \mathrm{u} \quad^{82} \mathrm{Kr},
81.9135 \mathrm{u}\)
\(^{83} \mathrm{Kr}, 82.9141 \mathrm{u} \quad^{84} \mathrm{Kr}, 83.9115
\mathrm{u} \quad^{86} \mathrm{Kr}, 85.9106 \mathrm{u}\)
The weighted-average atomic mass of \(\mathrm{Kr}\) is \(83.80 .\) Use these data
to calculate the percent natural abundances of the krypton isotopes.