20. NaCI, KCI, NaBr and KBr crystalline in FC lattices. Their anion and cation touch along the edge of unit cell. The dimensions of their unit cells are 562.8 pm, 627.7 pm, 596.2 pm, and 658.6 pm, respectively. From these data, what can you say about the size of the ionic radii (within an error of about 5%)?