What does it mean if a substance is hydrophilic?

A substance described as hydrophilic has a strong affinity for water. This characteristic means that it readily interacts with water molecules, often leading to its dissolution in water or the formation of hydrogen bonds with water. Hydrophilic substances can include ionic compounds and polar molecules, which can easily mix with water due to their charged or partially charged regions that attract water molecules.

This property is essential in many biological and chemical processes, such as the formation of cell membranes, where certain hydrophilic molecules interact with the aqueous environment. The behavior of hydrophilic substances contrasts with hydrophobic substances, which repel water and do not mix well with it.

In this context, the other choices do not accurately define hydrophilicity. While some substances do repel water and form droplets, that describes hydrophobicity, not hydrophilicity. The ability to dissolve in organic solvents pertains more to the chemical properties and solubility of a substance rather than its relationship with water. Lastly, being non-reactive with other substances does not convey any information about a substance's affinity for water. Therefore, the correct understanding that hydrophilic substances attract and mix with water aligns perfectly with the choice about having an affinity for water.