Answer: Option (C) is the correct answer.
Explanation:
The weak intermolecular forces that arise due to motion of electrons. As a result, there will be formation of temporary charges on the atoms of the compound.
HI, KBr and [tex]CH_{3}F[/tex] are all ionic in nature due to the presence of an electronegative atom in each of these compounds.
This electronegative atom will attract the electrons more towards itself due to which there will be formation of partial positive and partial negative charges on the atoms of the compound.
Hence, there will exist strong forces of attraction between these molecules.
Also, in case of [tex]CH_{3}OH[/tex] the alcoholic group has -I effect. Hence, there will also be formation of partial positive charge on [tex]CH_{3}[/tex] and partial negative charge on -OH group. Hence, it is also a polar molecule.
Whereas, [tex]CH_{3}CH_{3}[/tex] is a non-polar molecule. So, there will be development of temporary charges due to the movement of electrons.
Hence, only london dispersion forces will exist in a [tex]CH_{3}CH_{3}[/tex] molecule.
Thus, we can conclude that [tex]CH_{3}CH_{3}[/tex] species has London dispersion forces as the only intermolecular force.
