Final answer:
The correct answer is Choice C: "The curved surface is a concave meniscus which has formed because of capillary action." This occurs when the adhesive forces between water and glass are stronger than the cohesive forces within the water, causing the water to climb up the sides of the container, creating a concave shape.
Step-by-step explanation:
The phenomenon being described is known as the meniscus, which is the curved surface of a liquid in a container like a graduated cylinder. This curvature occurs due to the interplay between cohesive forces (which are the attractions between like molecules) and adhesive forces (which are the attractions between molecules of different substances).
For water in a glass container, the adhesive forces between the water molecules and the glass are stronger than the cohesive forces between the water molecules themselves. As a result, water tends to 'wet' the glass and climb up the sides, leading to a concave meniscus. This characteristic shape is an example of capillary action, a phenomenon which occurs when the adhesion to the walls is stronger than the cohesive forces within the liquid.
In mercury, however, the cohesive forces are stronger than the adhesive forces to glass, resulting in a convex meniscus. This condition, often referred to as capillary depression, causes the mercury to curve downward in a container.
Given this information, the correct choice that identifies the phenomenon and explains how it is formed is (Choice C): "The curved surface is a concave meniscus which has formed because of capillary action." This accounts for the observable shape of water in a glass tube as depicted in the question, which is created by the effect of surface tension and capillary action combined.