Chemistry - Liquid Solution Question with Solution | TestHub

When mercuric iodide is added to aqueous solution of Potassium iodide, the freezing point of solution will increase.
Potassium iodide ionizes in water as
$\mathrm{K}\mathrm{I}\to {\mathrm{K}}^{+}+{\mathrm{I}}^{-}$
When$\mathrm{H}\mathrm{g}{\mathrm{I}}_2$is added to it, it forms complex with KI
$2\mathrm{K}\mathrm{I}+\mathrm{H}\mathrm{g}{\mathrm{I}}_2\to {\mathrm{K}}_2\left[\mathrm{H}\mathrm{g}{\mathrm{I}}_4\right]\stackrel{}{\rightleftharpoons }2{\mathrm{K}}^{+}+[\mathrm{H}\mathrm{g}{\mathrm{I}}_4{]}^{-2}$
Hence, number of particle will decrease from 4 to 3. So, there would be less depression in freezing point and freezing point will increase.