Which pair is miscible?

Which pair is miscible?

• A. Water and Ethanol
• B. Oil and Water
• C. Sand and Water
• D. Gas and Water

Answer: (A)

This question tests miscibility and the principle that like dissolves like. Water and ethanol mix in all proportions because both are polar and can form hydrogen bonds with each other. The hydroxyl group in ethanol interacts with water through hydrogen bonding, allowing ethanol molecules to be solvated by water and vice versa, so no phase separation occurs and a single homogeneous liquid forms. In contrast, oil is nonpolar while water is highly polar, so their intermolecular interactions don’t favor mixing; oil and water separate into two layers. Sand is a solid that doesn’t dissolve in water, so it can only be dispersed as a suspension rather than forming a single phase. Gas and water can dissolve to some extent, but that does not create a single uniform liquid across all compositions, so they are not considered miscible in the same way as two liquids that form a homogeneous solution.

This question tests miscibility and the principle that like dissolves like. Water and ethanol mix in all proportions because both are polar and can form hydrogen bonds with each other. The hydroxyl group in ethanol interacts with water through hydrogen bonding, allowing ethanol molecules to be solvated by water and vice versa, so no phase separation occurs and a single homogeneous liquid forms.

In contrast, oil is nonpolar while water is highly polar, so their intermolecular interactions don’t favor mixing; oil and water separate into two layers. Sand is a solid that doesn’t dissolve in water, so it can only be dispersed as a suspension rather than forming a single phase. Gas and water can dissolve to some extent, but that does not create a single uniform liquid across all compositions, so they are not considered miscible in the same way as two liquids that form a homogeneous solution.