Chemistry - PERIODIC TABLE Question with Solution | TestHub

${\mathrm{Al}}^{3+},{\mathrm{Mg}}^{2+}$ and ${\mathrm{Na}}^{+}$ are isoelectronic ionic species. For monatomic ionic isoelectronic species as positive charge increases ionic size decreases.

The order of size of ${\mathrm{Na}}^{+}\&{ \mathrm{K}}^{+}$ is ${\mathrm{Na}}^{+}<{\mathrm{K}}^{+}$,

$\therefore$ Increasing order of ionic radii:  ${\mathrm{Al}}^{3+}<{\mathrm{Mg}}^{2+}<{\mathrm{Na}}^{+}<{\mathrm{K}}^{+}$