Chemistry - f-block Question with Solution | TestHub

The correct options are (A) and (D).

$l=3$ represents the $f$-subshell electrons.

In Set-1: Both Th and Ac have $0$ electrons in the $5f$ orbital, while both Ce²⁺ and Pr³⁺ have $2$ electrons in the $4f$ orbital.

In Set-4: Both Eu ($4f^{7}6s^2$) and Gd ($4f^{7}5d^{1}6s^2$) contain $7$ electrons in the $4f$ orbital, while both Yb ($4f^{14}6s^2$) and Lu ($4f^{14}5d^{1}6s^2$) contain $14$ electrons in the $4f$ orbital.