question_answer

Which of the following species has the same number of electrons in the outermost and penultimate shells? (a) \[{{\text{O}}^{\text{2}-}}\]                   (b) \[{{K}^{+}}\] (c) \[A{{l}^{3+}}\]                             (d) \[{{\text{F}}^{-}}\]

Answer:

               

Species	No. of electrons	Electronic configuration
\[{{O}^{2-}}\]	10	2, 8
\[{{K}^{+}}\]	18	2, 8, 8
\[A{{l}^{+3}}\]	10	2, 8
\[{{F}^{-}}\]	10	2, 8

From the above table, it is clear that \[{{K}^{+}}\] has same number of electrons in its outermost shell and penultimate shell.