Final answer:
Ethanol molecules are polar and form hydrogen bonds with polar water molecules, making them hydrophilic and allowing them to mix with water.
Step-by-step explanation:
When the polar molecules of ethanol, C2H5OH, are added to water, the correct answer is B: polar; form hydrogen bonds with the polar water molecules. Ethanol has a polar hydroxyl group (-OH) that can form hydrogen bonds with water, which is also polar. Therefore, ethanol molecules can interact with water through hydrogen bonding, resulting in ethanol being miscible with water and demonstrating hydrophilic properties.
The positive and negative charges in water molecules attract and form hydrogen bonds with the ethanol molecules, allowing the ethanol to dissolve in water.