Which of the following correctly ranks the materials by the strength of attraction between their atoms or molecules, from weakest to strongest: helium (He), water (H2O), sodium chloride (NaCl), and methane (CH4)?

• A. CH4 < He < NaCl < H2O
• B. H2O < CH4 < He < NaCl
• C. NaCl < H2O < CH4 < He
• D. He < CH4 < H2O < NaCl

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the types of intermolecular or interatomic forces present in each substance. Helium (He) is a noble gas with only very weak London dispersion forces (van der Waals forces). Methane (CH4) is a nonpolar molecule with weak London dispersion forces as well, but generally stronger than those in helium due to its larger size and more electrons.
2. Step 2: Water (H2O) is a polar molecule that exhibits hydrogen bonding, which is a much stronger intermolecular force than London dispersion forces. This means the attraction between water molecules is stronger than between helium or methane molecules.
3. Step 3: Sodium chloride (NaCl) is an ionic compound, where the attraction between ions (ionic bonds) is much stronger than any intermolecular forces in molecular substances. Ionic bonds are generally the strongest type of attraction among the given substances.
4. Step 4: Rank the substances from weakest to strongest based on the strength of their attractions: start with helium (weakest London dispersion), then methane (stronger London dispersion), followed by water (hydrogen bonding), and finally sodium chloride (ionic bonds).
5. Step 5: Confirm the correct order is: He < CH4 < H2O < NaCl, reflecting increasing strength of attraction between atoms or molecules.