Explanation:
The pressure exerted by vapors or gas on the surface of a liquid is known as vapor pressure.
This means that weaker is the intermolecular forces present in a substance more easily it can form vapors. As a result, it will have high vapor pressure.
As substance B has high vapor pressure which means that it has weak intermolecular forces.
Also, stronger is the intermolecular forces present in a substance more will be its boiling point. Hence, more energy or temperature is required to break the bonds. Hence, substance A has higher boiling point and high heat of vaporization.
When surrounding pressure is less than or equal to its vapor pressure then substance B boils into the gas phase. Hence, substance B will be a gas at 300 mm Hg.
Therefore, we can conclude that characteristics of the two substances will be as follows.
(a) Substance B - has weaker intermoclcular
(b) Substance A - has a higher boiling point
(c) Substance B - is a gas at 300 mm Hg
(d) Substance A - has a higher heat of vaporization
