Read the passage given below and answer the following questions :
Raoult's law states that for a solution of volatile liquids, the partial vapour pressure of each component of the solution is directly proportional to its mole fraction present in solution. Dalton's law of partial pressure states that the total pressure `P_("total")` over the solution phase in the container will be the sum of the partial pressures of the components of the solution and is given as:
`P_("total")`= `P_1`+ `P_2`

In comparison to a 0.01 M solution of glucose, the depression in freezing point of a 0.01 M `MgCl_2` solution is _ ___

Options

A. the same
B. about twice
C. about three times
D. about six times

Answer

C

Explanation

`DeltaT_f` =`iK_fm`, where i=l for glucose. glucose
`DeltaT_f^("glucose")= 1 xx K_f xx 0.01`
In case of `MgCl_2rArrMg^(2+)+ 2Cl^(-)`, where i = 3,
`T_f^(MgCl_2)= 3 xx 0.01 xx K_f` ,
implies `T_f^(MgCl_2)=3 xx DeltaT_f^("glucose")`
Hence, the depression in freezing point of `MgCl_2` is three times that of glucose.