Which statement describes immiscible substances?

Which statement describes immiscible substances?

• A. They dissolve in each other.
• B. They separate into layers and do not mix.
• C. They react to form a new compound.
• D. They dissolve only in water.

Answer: (B)

Immiscible liquids form distinct layers because their molecules do not interact favorably enough to mix; each liquid prefers interactions with itself rather than with the other. This is why oil and water separate into two layers—the polar water molecules hydrogen-bond with each other, while the nonpolar oil molecules interact mainly with themselves, so mixing would disrupt favorable interactions without providing new ones of similar strength. If substances dissolved in each other, you’d get a single homogeneous phase, which is not the case here. A chemical reaction would create a new substance rather than simply separating into layers. Dissolving only in water describes solubility with respect to water, not the inability of two liquids to mix with each other.

Immiscible liquids form distinct layers because their molecules do not interact favorably enough to mix; each liquid prefers interactions with itself rather than with the other. This is why oil and water separate into two layers—the polar water molecules hydrogen-bond with each other, while the nonpolar oil molecules interact mainly with themselves, so mixing would disrupt favorable interactions without providing new ones of similar strength.

If substances dissolved in each other, you’d get a single homogeneous phase, which is not the case here. A chemical reaction would create a new substance rather than simply separating into layers. Dissolving only in water describes solubility with respect to water, not the inability of two liquids to mix with each other.