Question

Which of the following has highest ionic radii?

• A. $C{r}^{3+}$
• B. $M{n}^{3+}$
• C. $F{e}^{3+}$
• D. $C{o}^{3+}$

Answer 1

The correct option is A $C{r}^{3+}$

$\text{Ionic Radii}\propto \frac{1}{\text{Atomic Number}}$
Ionic radius decreases from left to right in a period.
Across the period in transition elements, the nuclear charge increase due to poor shielding of d-orbitals which results in attraction of valence electrons and the size decrease.
Option (a) is correct.