Write the electron configurations for the following ions, and determine which have noble-gas configurations: \((\mathbf{a})\mathrm{Ru}^{3+}\) \((\mathbf{b}) \mathrm{As}^{3-},(\mathbf{c}) \mathrm{Y}^{3+},(\mathbf{d}) \mathrm{Pd}^{2+},(\mathbf{e}) \mathrm{Pb}^{2+},(\mathbf{f}) \mathrm{Au}^{3+}.\)

The electron configurations for the given ions are as follows: (a) \(Ru^{3+}\): \(1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 3d^{10} \ 4s^2 \ 4p^6 \ 4d^{7}\) - not a noble gas configuration (b) \(As^{3-}\): \(1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 3d^{10} \ 4s^2 \ 4p^6\) - matches Kr (noble gas configuration) (c) \(Y^{3+}\): \(1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 3d^{10} \ 4s^2 \ 4p^6\) - matches Kr (noble gas configuration) (d) \(Pd^{2+}\): \(1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 3d^{10} \ 4s^2 \ 4p^6 \ 4d^{8}\) - not a noble gas configuration (e) \(Pb^{2+}\): \(1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 3d^{10} \ 4s^2 \ 4p^6 \ 4d^{10} \ 4f^{14} \ 5s^2 \ 5p^6 \ 5d^{10} \ 6s^2 \ 6p^4\) - not a noble gas configuration (f) \(Au^{3+}\): \(1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 3d^{10} \ 4s^2 \ 4p^6 \ 4d^{10} \ 4f^{14} \ 5s^2 \ 5p^6 \ 5d^{9} \ 6s^1\) - not a noble gas configuration Out of these ions, only \(As^{3-}\) and \(Y^{3+}\) have noble-gas configurations (matching Kr).