Allen pours water into a graduated cylinder. He notices that the surface of the water is curved, as shown below.

Graduated cylinder showing curved surface of water where the sides of the water are higher than the center

Which of the following identifies this phenomenon and explains how it is formed?

Choose 1

(Choice A)

The curved surface is a convex meniscus which has formed because of capillary action.

(Choice B)

The curved surface is a convex meniscus which has formed because of surface tension.

(Choice C)

The curved surface is a concave meniscus which has formed because of surface tension.

(Choice D)

The curved surface is a concave meniscus which has formed because of capillary action.

When water is added to a graduated cylinder, having a surface where the sides of the water look higher than the center means that the curved surface is a concave meniscus which has formed because of surface tension (Choice C).

Explanation:

A meniscus is simply the curvature that the surface of a liquid acquires when it is in a container, such as a graduated cylinder. It is concave when there is attraction between molecules -water and glass- or it can be convex when both surfaces are repelled.

Water is a polar molecule, with the capacity to adhere to the surfaces it comes into contact with. This characteristic causes it to form a concave meniscus, as the outermost molecules adhere to the glass surface, while the surface tension of the water attracts the molecules from the centre downwards, causing the concavity.

Learn more:

Measuring with a graduated cylinder link

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.