Question

rank ions according to ionic radius

Answer 1

The Periodic Table is your friend.

(1) Going down a group, the radius of atoms gets larger, because you add more electron shells.

(2) Going across a period, the radius of atoms gets smaller, because the effective nuclear charge increases.

(3) Cations are usually smaller than neutral atoms, because they're missing one or more electrons. If an entire shell goes missing, e.g. Na -> Na+, the shrinkage is dramatic (40%).

(4) Anions are usually larger than neutral atoms, because they've got one or more extra electrons.