The Freezing Point (T_f) for T-Butanol Is 25

Multiple Choice

The freezing point (T_f) for t-butanol is 25.50°C, and K_f is 9.1°C/m. Usually t-butanol absorbs water on exposure to the air. If the freezing point of a 13.9-g sample of t-butanol is measured as 24.91°C, how many grams of water are present in the sample?

A) 7.0 g
B) 0.016 g
C) 0.21 g
D) 0.021 g
E) 0.76 g