An Unknown Nonelectrolyte and Nonvolatile Compound Is Dissolved in Enough

Multiple Choice

An unknown nonelectrolyte and nonvolatile compound is dissolved in enough pure water to make 348 mL of solution. The vapour pressure above the solution drops from 198.7 mbar to 196.7 mbar when 100.0 g of the compound is dissolved at constant temperature. Determine the molar mass of the unknown compound. Assume no change in volume occurs upon dissolution.

A) 689 g mol^-1
B) 342 g mol^-1
C) 180 g mol^-1
D) 509 g mol^-1
E) 243 g mol^-1