• # question_answer 55)   The electronic configuration of gadolinium (Z = 64) is : (a) $\left[ Xe \right]\text{ }4{{f}^{3}}5{{d}^{5}}\text{ }6{{s}^{2}}$           (b) $\left[ Xe \right]\text{ }4{{f}^{7}}5{{d}^{2}}6{{s}^{1}}$ (c) $[Xe]4{{f}^{7}}5{{d}^{1}}6{{s}^{2}}$               (d) $[Xe]4{{f}^{8}}5{{d}^{6}}6{{s}^{2}}$

(c) Gadolinium (64) is the seventh member of lanthanide series. Thus, it has 7 electrons on 4f-orbitals. General electronic configuration of lanthanide series is: $[Xe]4{{f}^{1-14}}5{{d}^{1}}6{{s}^{2}}$ On this basis, the electronic configuration of gadolinium is:                 $[Xe]4{{f}^{7}}5{{d}^{1}}6{{s}^{2}}$