On moving down a group of representative elements,both atomic and ionic radii increase with an increase in:

Which of the following is the incorrect order of ionic radius?

Assertion $(A)$: $Na^{+}$ and $Mg^{2+}$ ions are isoelectronic but the ionic radius of $Na^{+}$ is greater than that of $Mg^{2+}$.
Reason $(R)$: The effective nuclear charge of $Na^{+}$ ion is less than that of $Mg^{2+}$ ion.

The size of the following species increases in the order:

The ions $O^{2-}, F^{-}, Na^{+}, Mg^{2+}$ and $Al^{3+}$ are isoelectronic. Their ionic radii show

Largest in size out of $Na^{+}$,$Ne$,and $F^{-}$ is