The ions `O^(2-), F^(-), Na^(+), Mg^(2+)`, and `A1^(3+)` are isolectronic. Their ionic radii show

Options

A. a decrease from `O^(2-)` to `F^(-)`and then increase from `Na^(+)` to `A1^(3+)`
B. a significant increase from `O^(2-)` to `A1^(3+)`
C. a singnificant decrease form `O^(2-)`to `A1^(3+)`
D. an increase from `O^(2-)` to `F^(-)` and then decrease from `Na^(+)` to `A1^(3+)`

Answer

C

Explanation

They are all isoelectronic species. For such species,
Atomic radius `prop (1)/("Nuclear charge")`
`O^(2-)` has the minimum atomic number `(Z = 8)` while `A1^(3+)` has the maximum atomic number. Thus, there is a significant decreases is size from `O^(2-)` to `A1^(3+)`.