Which one of the following listed compounds should have the

Which one of the following listed compounds should have the lowest vapor pressure at a given tem­perature at which all these substances are in the liquid state?

A) CCl₃¾H

B) CCl₃¾Br

C) CCl₃¾Cl

D) CCl₃¾I

Solution

D) CCl₃¾I

As molecular weight of compound increases, the magnitude of intermolecular forces also increases and hence vapor pressure decreases. Thus, CCl₃¾I will have lowest vapor pressure