Among the given options, the molecule expected to have the highest melting point is NaCl.
Here’s the reasoning: NaCl (sodium chloride) is an ionic compound. In ionic compounds, the melting point is usually high due to the strong electrostatic forces of attraction between the positively charged sodium ions (Na+) and negatively charged chloride ions (Cl–). These ionic bonds require a significant amount of energy to break, resulting in a high melting point.
On the other hand, CCl4 (carbon tetrachloride) is a covalent molecule with relatively weaker van der Waals forces, so its melting point is much lower than that of NaCl. Cl2 (chlorine gas) and H2 (hydrogen gas) are nonpolar diatomic molecules with very weak intermolecular forces, making their melting points even lower.
Therefore, in comparison, NaCl has the highest melting point among the options provided.