Increasing amount of solid `Hgl_(2)` is added to `1 L` of an aqueous solution containing `0.1 mol KI`. Which fo the following graphs do represent the variation of freezing point of the resulting with the amount of `Hgi_(2)` added?

Options

A.
B.
C.
D.

Answer

B

Explanation

When `Hgl_2` is added to KI:
`HgI_2+2KItoK_2HgI_4`
`{:("Moles",0.05,0.1),(-,-,0.05):}`
`rArr` 0.05 moles of `HgI_2` are required for its complex reaction with KI.
Thus, as `HgI_2` is being added, the number of solute molecules will decrease causing `DeltaT_f` to decrease `rArr` (Causing `T_f` to increase).When whole of KI has been converted to `K_2HgI_4`, further addition of `HgI_2` does not change `T_f` since it is a sparingly soluble salt.