...Questions? Please explain how come its true! I would greatly appreciate! I have an exam comming up and this is a sample practice exam and I don't have the answer key! I would greatly appreciate if you can explain in details so that I can compare my notes. Thanks soooo much!

6) A solution is prepared by dissolving 38.6 g sucrose (C12H22O11) in 495 g of water. Determine the mole fraction of sucrose if the final volume of the solution is 508 mL.

A) 7.80 × 10^-2
B) 2.45 × 10^-3
C) 7.23 × 10^-2
D) 4.09 × 10^-3
E) 1.28 × 10^-3


7) Choose the aqueous solution with the LOWEST vapor pressure. These are all solutions of nonvolatile solutes and you should assume ideal van?t Hoff factors where applicable.
A) 0.030 m LiC2H3O2
B) 0.120 m C2H6O2
C) 0.040 m (NH4)2SO4
D) 0.060 m K2CO3
E) They all have the same vapor pressure.

8) The boiling point elevation of an aqueous sucrose solution is found to be 0.39°C. What mass of sucrose (molar mass=342.30 g/mol) is contained in 500.0 g of the solution? Kb (water) =0.512°C/m.
A) 223 g sucrose
B) 528 g sucrose
C) 130. g sucrose
D) 762 g sucrose
E) 261 g sucrose