When mercuric iodide is added to the aqueous solution of potassium iodide, then:

Options

A. freezing point is raised
B. freezing point does not change
C. freezing point is lowered
D. boiling poing does not change

Answer

A

Explanation

When `HgI_(2)` is added to the aqueous solution of KI following reaction takes place.
`2KI+HgI_(2)rarrK_(2)[HgI_(4)]hArr2K^(+)+[HgI_(4)]^(2-)`
Thus there is a net decrease in number of ions present in solution. Two formula units of KI i.e., four ions decrease to three ions in `K_(2)[HgI_(4)]`.
As number of ions decreases `DeltaT_(f)` decrease of f.p. is raised.