Final answer:
Methylamine (CH3NH2) has the strongest intermolecular forces among the choices listed due to the presence of hydrogen bonds, which are stronger than the dipole-dipole interactions in H2S and NO, and London dispersion forces in Cl2 and Rn.
Step-by-step explanation:
The strongest intermolecular forces are expected to be found in substances with hydrogen bonding or permanent dipoles. Among the given choices, CH3NH2 (methylamine) is expected to have the strongest intermolecular forces, specifically hydrogen bonding. Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom like nitrogen, oxygen, or fluorine, and is in close proximity to another electronegative atom with a lone pair of electrons.
Substances like H2S and NO may have dipole-dipole interactions but these are weaker compared to hydrogen bonds. Moreover, substances like Cl2 and Rn (radon) exhibit only London dispersion forces, which are the weakest type of intermolecular force.
Therefore, methylamine (CH3NH2) has stronger intermolecular attractions than the other substances due to hydrogen bonding.