Which statement best explains why oil and water do not mix?

• A. Oil molecules form hydrogen bonds with water molecules, causing separation.
• B. Water is nonpolar and oil is polar, so they repel each other.
• C. Oil and water have similar densities, preventing them from mixing.
• D. Oil is nonpolar and water is polar, so there are weak intermolecular forces between them.

Answer: (D)

Verified step by step guidance

1. Identify the polarity of water and oil molecules: Water is a polar molecule due to its bent shape and electronegativity difference between hydrogen and oxygen, while oil molecules are generally nonpolar hydrocarbons.
2. Understand the concept of intermolecular forces: Polar molecules like water exhibit strong dipole-dipole interactions and hydrogen bonding, whereas nonpolar molecules like oil primarily exhibit weaker London dispersion forces.
3. Apply the principle 'like dissolves like': Polar substances tend to mix well with other polar substances, and nonpolar substances mix well with nonpolar substances, but polar and nonpolar substances do not mix effectively due to differences in intermolecular forces.
4. Explain why oil and water do not mix: Because water is polar and oil is nonpolar, the intermolecular forces between water molecules are much stronger than those between water and oil molecules, leading to phase separation.
5. Conclude that the key reason for immiscibility is the difference in polarity and the resulting weak intermolecular forces between oil and water molecules.