Question

the boiling point of ch4 is much lower than that of nh3. this is because:
hydrogen bonding exist between nh3 molecules
ch4 is a polar molecule
ion - dipole interactions occur between nh3 molecules
dipole - dipole interactions occur between ch4 molecules
nh3 is a non - polar molecule

Explanation:

Boiling points depend on intermolecular forces. $\text{NH}_3$ has hydrogen bonding (strong intermolecular force) because it contains N-H bonds (N is highly electronegative). $\text{CH}_4$ is nonpolar with only weak London dispersion forces. Stronger forces in $\text{NH}_3$ raise its boiling point. Other options are incorrect: $\text{CH}_4$ is nonpolar, $\text{NH}_3$ has hydrogen bonding not ion-dipole/dipole-dipole alone, and $\text{NH}_3$ is polar.

Answer:

hydrogen bonding exist between $\text{NH}_3$ molecules