Which of the following best explains why water and oil do not mix?

• A. Both water and oil are nonpolar substances, so they repel each other.
• B. Water and oil have similar densities, which prevents them from mixing.
• C. Oil molecules form ionic bonds with water molecules, causing separation.
• D. Water molecules are polar and form hydrogen bonds, while oil molecules are nonpolar and interact via London dispersion forces, making them immiscible.

Answer: (D)

Verified step by step guidance

1. Understand the nature of water molecules: Water is a polar molecule due to the difference in electronegativity between hydrogen and oxygen atoms, and its bent shape, which creates a dipole moment.
2. Recognize that water molecules form hydrogen bonds with each other, which are strong intermolecular forces arising from the attraction between the partial positive charge on hydrogen and the partial negative charge on oxygen.
3. Understand that oil molecules are generally nonpolar and interact primarily through London dispersion forces, which are weaker intermolecular forces caused by temporary dipoles in molecules.
4. Recall the principle 'like dissolves like,' meaning polar substances tend to mix with other polar substances, and nonpolar substances mix with nonpolar substances, but polar and nonpolar substances do not mix well.
5. Conclude that because water is polar and forms hydrogen bonds, and oil is nonpolar with only London dispersion forces, their differing intermolecular forces prevent them from mixing, making them immiscible.