Question

What type of intermolecular forces exists between the following pair of compounds?
\[N{H_3}\] and \[{C_6}{H_6}\]
a.Dipole-induced dipole
b.Dipole-dipole forces
c.Dispersion forces
d.None of the above

Answer 1

Hint: One must identify whether a molecule is polar or nonpolar. A polar molecule will have an electric dipole moment with a negative and a positive charge end. Whereas a nonpolar molecule has no separation of this. Thus the polar molecule have will induce a dipole to the other molecule as polar molecule possess permanent dipole

Complete Answer:
Before answering the question let us first understand what intermolecular forces are and discuss each option one by one.
Intermolecular forces, as the name suggests, is the force of attraction or repulsion which acts between atoms or neighboring particles, mediating interaction between molecules. The force which holds the molecule together is called the intramolecular forces. A very familiar example is the bond that exists between the neighboring water molecules in ice.
A dipole-dipole force occurs between those molecules which have permanent dipoles. Since only \[N{H_3}\] have a permanent dipole, therefore we can eliminate this option.
Dispersion forces exist between neutral atoms such as noble gases or nonpolar molecules such as \[{O_2}\], \[{H_2}\]. Therefore we can eliminate this option as well.
Now we are left with the option of dipole-induced forces. It occurs between a polar molecule having a permanent dipole moment and a nonpolar molecule with zero dipole moment. As we know \[N{H_3}\] is a polar molecule and \[{C_6}{H_6}\] is a nonpolar molecule.

Therefore option a is the correct option.

Note:
Induced dipole moment depends on the dipole moment present in the permanent dipole and the polarizability of the electrically neutral molecule. Another type of intermolecular force is ion-dipole force. It occurs between an anion or a cation and a polar molecule. Dispersion forces are also known as London forces. They are very weak forces.