SF4 as a covalent molecular compound

Steps:

• Determine SF4 structure: Sulfur (6 valence e⁻) bonds to 4 fluorines (7 e⁻ each), total 34 valence electrons (17 pairs: 4 bonding pairs, 10 lone pairs on F, 3 on S).
• Evaluate A: 17 pairs total, not 16.
• Evaluate B: Sulfur, not silicon; S achieves expanded octet (10 e⁻), F achieves neon-like (8 e⁻).
• Evaluate C: Covalent, no ions or delocalized e⁻ for conduction.
• Evaluate D: Matches molecular compounds with weak van der Waals forces.

Why D is correct:

• SF4 is a simple covalent molecule; low melting points result from weak intermolecular forces (van der Waals), per molecular compound properties.

Why the others are wrong:

• A: Total valence electrons form 17 pairs, not 16.
• B: Molecule contains sulfur (not silicon); only F has neon configuration.
• C: Lacks free ions or electrons, so non-conductor when molten.

Final answer: D