Drops of mercury, water and naphtha (lighter fluid) are placed on smooth flat surface. The mercury drop is almost a perfect sphere. The water drop is a flattened sphere. The naphtha however spreads out over the surface. What do these observations tell you about the cohesive force in mercury water and naphtha?

Question

(b) Which liquid would vaporize easiest?
(c) Which would have the lowest boiling point? Explain.

Answer 1

Here is a good site for reading about cohesive versus adhesive forces. As you can see the cohesive forces for mercury are highest, water is next, and the cohesion among naphtha molecules is very low. After reading the article you should be able to answer the questions.
http://en.wikipedia.org/wiki/Cohesion_(chemistry)

Answer 2

Yeah
From the question Naphtha is least cohesive and most adhesive. Whereas mercury is the exact opposite. Water is in the middle of these two.
But does it necessarily mean that the liquid which is the most adhesive will vapourize easiest and have the lowest boiling point?

Answer 3

I don't think I would express it in the form of adhesive but rather in cohesive. It does stand to reason that the liquid with the most cohesive forces (those between the same molecules) will have the highest boiling point and those with the least cohesiveness will have the lowest boiling point.

Answer 4

Based on the evidence included in the question, cohesive forces (attraction between particles within a material) decrease: Hg > H2O > naphtha.
Next, consider how the boiling point is related to cohesive forces and deduce whether the boiling points compare in the same way or in the reverse way.