Why do certain liquids form separate layers when combined in a container?

• A. Because the temperature of the liquids is always different.
• B. Because liquids always form layers due to gravity, regardless of their composition.
• C. Because the liquids have different densities and do not mix due to differences in intermolecular forces.
• D. Because all liquids always repel each other regardless of their properties.

Answer: (C)

Verified step by step guidance

1. Understand that when two liquids are combined, whether they mix or form separate layers depends on their physical and chemical properties, not just temperature or gravity alone.
2. Recognize that liquids with different densities tend to separate because the denser liquid will settle below the less dense one due to gravitational forces acting on their mass.
3. Consider the role of intermolecular forces: if the liquids have very different types or strengths of intermolecular forces, they may not mix well, leading to immiscibility and layer formation.
4. Recall that miscibility depends on the similarity of intermolecular forces; liquids with similar forces tend to mix, while those with different forces tend to separate.
5. Conclude that the primary reason certain liquids form separate layers is because they have different densities and do not mix due to differences in their intermolecular forces.