Which one of the following sets of ions represents the collection of isoelectronic species?

Options

A. `K^(+),Ca^(2+),Sc^(3+),Cl^(-)`
B. `Na^(+),Mg^(2+),Al^(3+),Cl^(-)`
C. `K^(+),Cl^(-),Mg^(2+),Sc^(3+)
D. Na^(+),Ca^(2+),Sc^(3+),F^(-)`

Answer

A

Explanation

`K^(+)` (Z=9), `Ca^(2+)` (Z=20) , `Sc^(3+)` (Z=21) and `Cl^(-)` (Z=17) , all have 18 electrons each and as such are isoelectronic.