Which best explains why the meniscus of mercury in a glass tube is convex?

• A. Mercury has a lower surface tension than water.
• B. The cohesive forces between mercury atoms are stronger than the adhesive forces between mercury and glass.
• C. Mercury forms hydrogen bonds with the glass surface.
• D. The adhesive forces between mercury and glass are stronger than the cohesive forces between mercury atoms.

Answer: (B)

Verified step by step guidance

1. Understand the concept of meniscus formation: The shape of the meniscus in a liquid inside a tube depends on the balance between cohesive forces (attraction between like molecules) and adhesive forces (attraction between unlike molecules, such as liquid and tube surface).
2. Recall that a concave meniscus forms when adhesive forces between the liquid and the container are stronger than the cohesive forces within the liquid, causing the liquid to climb up the walls of the container.
3. Recognize that a convex meniscus forms when cohesive forces within the liquid are stronger than the adhesive forces between the liquid and the container, causing the liquid to pull away from the walls and curve downward.
4. Apply this to mercury in a glass tube: Mercury atoms have strong cohesive forces due to metallic bonding, which are stronger than the adhesive forces between mercury and the glass surface.
5. Conclude that because the cohesive forces in mercury dominate over adhesive forces with glass, the meniscus of mercury is convex.