The ions `O^(2-), F^(-), Na^(+), Mg^(2+)`, and `Al^(3+)` are isoelectronic. Their ionic radii show

Options

A. a decreases from `O^(2-)` to `F^(-)` and then increases from `Na^(+)` to `Al^(3+)`
B. a significant increase from `O^(2-)` to `Al^(3+)`
C. a significant decrease from `O^(2)` to `Al^(3+)`
D. an increases from `O^(2-)` to `F^(-)` and then decrease from `Na^(+)` to `Al^(3+)`.

Answer

C

Explanation

For isoelectronic species more the nuclear charges lesser is the ionic radius.
`O^(2-) (Z=8) , F^(-) (Z=9), Na^(+) (Z=11) , Mg^(2+) (Z=12), Al^(3+) (Z=13)`. Thus `O^(2-)` largest and `Al^(3+)` is smallest