Gadolinium belongs of 4f series. Its atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?

• A

  $\left[\mathrm{X}\mathrm{e}\right]4{\mathrm{f}}^{8}6{\mathrm{d}}^2$
• B

  $\left[\mathrm{X}\mathrm{e}\right]4{\mathrm{f}}^{9}5{\mathrm{s}}^1$
• Correct answer
  C

  $\left[\mathrm{X}\mathrm{e}\right]4{\mathrm{f}}^{7}5{\mathrm{d}}^{1}6{\mathrm{s}}^2$
• D

  $\left[\mathrm{X}\mathrm{e}\right]4{\mathrm{f}}^{6}5{\mathrm{d}}^{2}6{\mathrm{s}}^2$

Hence, the correct answer is option: 'C'.