Diethyl Ether Has a Vapor Pressure of 400 $\degree$ C When a Sample of Benzoic Acid Is Dissolved in 18

Multiple Choice

Diethyl ether has a vapor pressure of 400.0 torr at 18 $\degree$ C. When a sample of benzoic acid is dissolved in ether, the vapor pressure of the solution is 342 torr. What is the mole fraction of benzoic acid in the solution?

A) 0.0169
B) 0.0197
C) 0.145
D) 0.855
E) None of these choices is correct.