Q. Identify the least stable ion amongst the following
A) $Li^{-}$
B) $Be^{-}$
C) $B^{-}$
D) $C^{-}$
Explanation
(b)
$Li^{-} = 1s^{2},2s^{2}$(In it all subshells are saturated so, it is stable)
$Be^{-} = 1s^{2},2s^{2},2p^{1}$ (very much less stable)
$B^{-} = 1s^{2},2s^{2},2p^{2}$ (less stable)
$C^{-} = 1s^{2},2s^{2},2p^{3}$ (stable due to presence of half-filled 2$p$-subshell)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.