If CI₂ gas is passed into aqueous solution of KI containing some CCl₄ and the mixture is shaken then

$2\mathrm{KI}+{\mathrm{Cl}}_2\to 2\mathrm{KCl}+{\mathrm{I}}_2$
${\mathrm{I}}_2+{\mathrm{CCl}}_4\to \text{ Violet Colour }$
Note: The excess of Cl₂ should be avoided. The layer may become colourless due to conversion of I₂ to HIO₃
${\mathrm{I}}_2+5{\mathrm{Cl}}_2+6{\mathrm{H}}_2\mathrm{O}\to 2{\mathrm{HIO}}_3+10\mathrm{HCl}$
$\text{ In case of }{\mathrm{Br}}_2:{\mathrm{Br}}_2+2{\mathrm{H}}_2\mathrm{O}+{\mathrm{Cl}}_2\to 2\mathrm{HBrO}+2\mathrm{HCl}$
The layer test is based upon distribution law