Question

.            The molar enthalpy of vaporization of molecular compounds is

                A) always negative  

                B) always positive  

                C) negative if the boiling point is below room temperature but positive if the boiling point is above room    temperature  

                D) can be negative or positive depending on the substance.

Answer 1

(B) Always positive

Because ,enthalpy of vaporistion is the process in which heat is absorbed by the system to change it's state from liquid to gas and heat absorbed by system is always positive.

Heat lost by the system is negative (the condensation process)

i hope it helps..