Comparing ionic vs. covalent nature of Na and Si compounds

Steps:

• Identify bonding: Sodium forms ionic compounds (NaCl, Na2O); silicon forms covalent compounds (SiCl4, SiO2).
• Evaluate reactivity (A): Covalent SiCl4 hydrolyzes with water to form SiO2 and HCl; ionic NaCl dissolves without reaction.
• Evaluate melting points (B, C): Giant covalent SiO2 has high mp due to strong network; ionic Na2O/NaCl have moderate/high mp from lattice energy; molecular SiCl4 has low mp due to weak van der Waals forces.
• Conclude: Statements A, B, C align with bonding types; D lacks details.

Why C is correct:

• SiCl4 is simple molecular (covalent), with low mp (-70°C) from weak intermolecular forces; NaCl is ionic lattice with high mp (801°C) per Fajans' rules on lattice energy.

Why the others are wrong:

• A is correct based on hydrolysis of covalent chlorides vs. stability of ionic salts.
• B is correct as giant covalent SiO2 (mp 1710°C) exceeds ionic Na2O (mp 1132°C).
• D: Not enough information.

Final answer: C