When 200 Grams of an Unknown Compound Are Dissolved in 500

Multiple Choice

When 20.0 grams of an unknown compound are dissolved in 500. grams of benzene, the freezing point of the resulting solution is 3.77 ^$\circ$ C. The freezing point of pure benzene is 5.444 ^$\circ$ C, and the K_f for benzene is 5.12 ^$\circ$ C/m. What is the molar mass of the unknown compound

A) 110 g/mol
B) 120 g/mol
C) 130 g/mol
D) 140 g/mol
E) None of the above