Which comparisons of an ion with its parent atom are correct?

A $S X^{2 -}$ is smaller than $S$ .
B $Mg X^{2 +}$ is larger than $Mg$ .
C $Fe X^{3 +}$ is smaller than $Fe X^{2 +}$ .
D $Cl X^{-}$ is larger than $Cl$ .

Answer: C, D

Anions are larger than their atoms because electron repulsion increases at fixed nuclear charge. Cations are smaller than their atoms, and a higher positive charge on the same element gives a smaller ion.

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