Question

The reason for the stability of $G{d}^{+3}$ ion is:

• A. A half filled 4f subshell
• B. A completely filled 4f subshell
• C. It possesses the general electronic configuration of a noble gas
• D. It has an empty 4f subshell

Answer 1

The correct option is A A half filled 4f subshell

Electronic configuration of gadolinium:
$Gd=\left[Xe\right]4f^{7}5d^{1}6s^2$
$G{d}^{+3}=\left[Xe\right]4f^{7}5d^{0}6s^0$