# Which compound forms a colored aqueous solution?

$(a)\;CaCl_{22} \\(b)\;CrCl_3 \\ (c)\;NaOH \\ (d)\;KBr$

Colored aqueous solutions are a characteristic of transition compounds.
The only transition compound in the above choices is $CrCl_3.$
$Cr$ is a transition element.
Hence b is the correct answer.