Asolution of methanol and water has a mole fraction of water of 0.312 and a total vapor pressure of 21 torr at 39.9 degrees c. the vapor pressures of pure methanol and pure water at this temperature are 256 torr and 55.3 torr , respectively.
is the solution ideal? no, it isnt.
what can you say about the relative strengths of the solute-solvent interactions compared to the solute-solute and solvent-solvent interactions?
a. the methanol-water interactions are stronger than the methanol-methanol and water-water interactions.
b. the methanol-water interactions are weaker than the methanol-methanol and water-water interactions.

Explanation:

Given the details, we can say that

Pure methanol is a volatile solvent as the vapour pressure has a high value. This means that methanol - methanol intermolecular forces are weak in comparisson to water - water forces. When having about 30% of water in a methanol mixture, the mixture Pv decreased, showing that it is not a volatile mixture, so then there are strong intermolecular interactions between methanol - water, part of it due to the hydrogen bonds.

Based on the conditions given as vapor pressure is 256 torr,the methanol-water interactions are stronger than the methanol-methanol and water-water interactions is the correct option.

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.