Which best explains why water is able to "stick" to the side of glass?

• A. Hydrophobic interactions between water and glass cause water to adhere to the surface.
• B. Surface tension prevents water from interacting with glass.
• C. Cohesion between water molecules causes water to stick to glass.
• D. Adhesion between water molecules and glass allows water to cling to the surface.

Answer: (D)

Verified step by step guidance

1. Understand the key terms in the question: 'adhesion' refers to the attraction between different substances, while 'cohesion' refers to the attraction between molecules of the same substance (e.g., water molecules).
2. Recognize that water molecules are polar, meaning they have a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. This polarity allows water to form hydrogen bonds with other polar substances, such as glass.
3. Glass is made of silica (SiO₂), which has polar hydroxyl (-OH) groups on its surface. These groups can form hydrogen bonds with water molecules, leading to adhesion.
4. Eliminate incorrect options: Hydrophobic interactions are not relevant here because both water and glass are polar. Surface tension is a property of water that arises from cohesion, but it does not explain why water sticks to glass. Cohesion refers to water molecules sticking to each other, not to glass.
5. Conclude that the correct explanation is adhesion between water molecules and the polar surface of glass, which allows water to cling to the surface.