Q. The least stable ion among the following is
A) ${Li}^{-}$
B) $Be^{-}$
C) $B^{-}$
D) $C^{-}$
Explanation
(b)
$Be(1s^{2}2s^{2})$ because of the presence of fully filled $2s$-subshell has least tendency to take up an electron. Hence, $Be^{-}$ is least stable
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.