Step 1:

Total mass of the mixture is 20 g.

Freezing point of the solution is .

At ideal conditions:

Total mass of mixture =Mass of sucrose + Mass of the 

Let mass of the sucrose be grams.

Molar Mass of the sucrose is 324.496 g/mol

Amount of sucrose in moles is

Mass of is grams.

Molar Mass of the is 58.44 g/mol

Mass of the solute = Mass of the solvent + Mass of the solution.

.

Step 2:

Freezing point of water , where

is the change in temperature and ,

is the van t Hoff factor,

is the molality of the solution and

is the molality depression constant = .

Freezing point :

Here for sucrose is 1.

for sodium chloride is 2.

Substitute

Mass of the sucrose is 14.55 g.

Mass of the sodium chloride is 20-14.55 = 5.45 g.

Step 3:

Mass percentage of the substance is .

Mass percentage of Sucrose:

Mass percentage of Sodium chloride:

Mole fraction of substance is

Mole fraction of sucrose:

Solution:

Mass percentage of Sucrose is 72.8%

Mass percentage of Sodium chloride is 27.25%

Mole fraction of sucrose is 0.343.