The reason for the stability of `Gd^(3+)` ion is

Options

A. 4f-subshell-half filled
B. 4f subshell-completely filled
C. Possesses the general electronic configuration of noble gases
D. 4f-subshell empty.

Answer

a

Explanation

`Gd(Z=64)implies4f^75d^16s^2`
`Gd^3=4f^7`
`Gd^(3+)` is stable due to the presence of exactly half-filled 4f-subshell.