Thyroxine, an Important Hormone That Controls the Rate of Metabolism $\circ$

Multiple Choice

Thyroxine, an important hormone that controls the rate of metabolism in the body, can be isolated from the thyroid gland. If 0.455 g of thyroxine is dissolved in 10.0 g of benzene, the freezing point of the solution is 5.144 ^$\circ$ C. Pure benzene freezes at 5.444 ^$\circ$ C and has a K_f of 5.12 ^$\circ$ C/m. What is the molar mass of thyroxine

A) 777 g/mol
B) 787 g/mol
C) 797 g/mol
D) 807 g/mol
E) None of the above