The ion with smallest radius among the following is
The ion with smallest radius among the following is
$\mathrm{Ca}^{2+}$
$\mathrm{K}^{+}$
$\mathrm{Ti}^{4+}$
$\mathrm{Sc}^{3+}$
Solution
All the given species have the elements belonging to the same period and ionic radii decrease in a period from left to right. $\mathrm{Ti}^{4+}$ lies to the right of the other species and would be even more small due to a greater positive charge.
Thus, order of radii would be :-
$`
\mathrm{K}^{+}>\mathrm{Ca}^{2+}>\mathrm{Sc}^{3+}>\mathrm{Ti}^{4+}
$