MCQ
$A{l^{3 + }}$ has a lower ionic radius than $M{g^{2 + }}$ because
  • A
    $Mg$ atom has less number of neutrons than $Al$
  • $A{l^{3 + }}$ has a higher nuclear charge than $M{g^{2 + }}$
  • C
    Their electronegativities are different
  • D
    $Al$ has a lower ionisation potential than $Mg$ atom

Answer

Correct option: B.
$A{l^{3 + }}$ has a higher nuclear charge than $M{g^{2 + }}$
b
$Al ^{3+}$ and $Mg ^{2+}$ have equal number of electrons and are, therefore, isoelectronic.

For iso-electronic species, size depends upon the effective nuclear charge and size is inversely proportional to the effective nuclear charge. More is the positive charge, more is the effective nuclear charge and thus, lesser is the size.

Since the effective nuclear charge is greater in $Al ^{3+}$ than $Mg ^{2+}$, it has a smaller size than $Mg ^{2+}$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free