Final answer:
The predominant intermolecular force in ammonia is hydrogen bonding, while methane experiences London dispersion forces, and dichloromethane experiences a combination of dipole-dipole interactions and London dispersion forces.
Step-by-step explanation:
The predominant intermolecular force in the liquid state of ammonia (NH₃) is hydrogen bonding. Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom, such as nitrogen, oxygen, or fluorine. In ammonia, the nitrogen atom is bonded to three hydrogen atoms, and the electronegativity difference between nitrogen and hydrogen creates a relatively strong hydrogen bond between ammonia molecules.
For methane (CH₄), the predominant intermolecular force is London dispersion forces. London dispersion forces are temporary attractive forces that occur due to momentary shifts in electron distribution within molecules. Since methane is a nonpolar molecule, it experiences only London dispersion forces as there are no permanent dipoles present in the molecule.
In the case of dichloromethane (CH₂Cl₂), the predominant intermolecular force is a combination of dipole-dipole interactions and London dispersion forces. Dichloromethane is a polar molecule due to the presence of chlorine atoms, which creates permanent dipoles. The dipole-dipole interactions are stronger than London dispersion forces in this compound.