Question

Which of the following has the smallest ionic radii?

• A. $L{i}^{+}$
• B. $B{e}^{2+}$
• C. $B^{3+}$
• D. $L{i}^{2+}$

Answer 1

The correct option is C $B^{3+}$

$L{i}^{+},B{e}^{2+}and{B}^{3+}$ are isoelectronic species.

In such a series, size decreases as the effective nuclear charge (atomic number) of the ion increases.

Therefore the increasing order of radii: $B^{3+}<B{e}^{2+}<L{i}^{+}$