Which of the following is an example of cohesion in water?

• A. Water dissolving salt crystals
• B. Water climbing up a paper towel dipped in a glass
• C. Water droplets forming beads on a waxed car surface
• D. Water spreading out on a glass surface

Answer: (C)

Verified step by step guidance

1. Understand the concept of cohesion: Cohesion refers to the attraction between molecules of the same substance. In the case of water, cohesion is primarily due to hydrogen bonding between water molecules.
2. Analyze the options provided: Evaluate each example to determine if it demonstrates cohesion, which involves water molecules sticking to each other rather than interacting with other substances.
3. Option 1: Water dissolving salt crystals - This demonstrates adhesion, where water interacts with and breaks apart salt molecules, not cohesion.
4. Option 2: Water climbing up a paper towel dipped in a glass - This is an example of capillary action, which involves both adhesion (water sticking to the paper towel) and cohesion (water molecules pulling each other along). It is not purely cohesion.
5. Option 3: Water droplets forming beads on a waxed car surface - This is an example of cohesion, as water molecules stick together to form beads due to hydrogen bonding, resisting spreading out on the waxed surface.