Answer: pentanol>pentanal>pentane
Explanation:
Pentanol will have the highest viscosity, boiling point and surface tension because it has the highest degree of intermolecular interaction. The molecules of pentanol are held together by strong intermolecular hydrogen bonds which raises its boiling point. This degree of intermolecular interaction is absent in pentanal and pentane. They have much lower boiling points with pentane having the lowest boiling point due to the presence of weak London forces.
