Which of the following solids would be expected to display the highest melting point?

• A. C6H12O6 (glucose)
• B. I2 (iodine)
• C. CO2 (dry ice)
• D. NaCl (sodium chloride)

Answer: (D)

Verified step by step guidance

1. Step 1: Identify the types of intermolecular or interatomic forces present in each solid. For example, glucose (C6H12O6) has hydrogen bonding and dipole-dipole interactions, iodine (I2) is held together by London dispersion forces, carbon dioxide (CO2) is a molecular solid with weak dispersion forces, and sodium chloride (NaCl) is an ionic solid with strong ionic bonds.
2. Step 2: Understand that melting point generally increases with the strength of the forces holding the solid together. Ionic bonds are typically much stronger than hydrogen bonds, dipole interactions, or dispersion forces.
3. Step 3: Compare the strength of the forces: NaCl's ionic bonds are much stronger than the hydrogen bonds in glucose, which are stronger than the dispersion forces in iodine and CO2.
4. Step 4: Conclude that because NaCl has the strongest bonding (ionic bonds), it will have the highest melting point among the given solids.
5. Step 5: Remember that molecular solids like CO2 and I2 have relatively low melting points due to weak intermolecular forces, while covalent network solids or ionic solids tend to have much higher melting points.