Question

Which compound among the following has more covalent character ?

• A. $AlC{l}_3$
• B. $Al{I}_3$
• C. $Mg{I}_2$
• D. $NaI$

Answer 1

Answer: (B)

$Al{I}_3$

Aluminum triiode has more covalent character due to high charge to size ratio of $Al\left(III\right)$ cation and small charge to size ratio of iodide anion.
Thus, the cation has high polarizing power and the anion has high polarizability.