which of the following pairs of ions would have the greatest coulmbic attraction in a solid compound?

Question

1. Mg2+, O2-
2. Mg2+, Se2-
3. Mg2+, S2-

Answer 1

1. Mg2+, O2-
The closer the positive-negative ion pairs are, the greater the Coulombic attraction is between them. Since the atomic radius of O-- is smaller than S-- which is in turn smaller than Se--, Mg++ and O-- can be packed much tight.

Answer 2

LiF Cs2O CaBr2