Question

what is the relationship between vapor pressure and boiling point?
a the higher the vapor pressure the higher the boiling point.
b the higher the vapor pressure the lower the boiling point.
c the lower the vapor pressure the lower the boiling point.
d there is no relationship between vapor pressure and boiling point.

Explanation:

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid phase. The boiling point of a liquid is the temperature at which its vapor pressure equals the external pressure. Substances with higher vapor pressures reach this equilibrium at lower temperatures. For example, consider two liquids. Liquid A has a high vapor pressure. It means more molecules of liquid A escape into the vapor phase easily. So, it doesn't need a very high temperature to make its vapor pressure equal to the external pressure (like atmospheric pressure). On the other hand, a liquid with low vapor pressure (liquid B) requires more energy (higher temperature) to get enough molecules into the vapor phase to match the external pressure.

Answer:

B. The higher the vapor pressure the lower the boiling point.