The rising of a liquid in an open and ended glass tube of narrow bore is

Analyze the question: The question asks for the name of the phenomenon in which a liquid rises in a narrow-bore, open-ended glass tube.

Explain the concept:

• Capillarity (capillary action): a liquid rises or falls in a narrow tube. It happens because of the combined effect of adhesion (liquid molecules attracted to the glass) and cohesion/surface tension within the liquid.
• Osmosis: water moves through a semi-permeable membrane. It has nothing to do with a glass tube.
• Adhesion: the force of attraction between unlike molecules, such as water and glass. It is one cause of the rise but not the name of the phenomenon.
• Surface tension: the property of a liquid surface that makes it behave like a stretched elastic skin. It also contributes to the rise but is not the phenomenon itself.

Solution:

1. Water in contact with the glass wall is pulled upward by adhesive forces, so the liquid surface curves (the meniscus).
2. Surface tension acts along this curved surface and pulls the liquid up the tube.
3. The liquid keeps rising until the weight of the raised column balances this upward pull.
4. The height is given by h = 2T cosθ / (rρg). The narrower the tube (smaller r), the higher the liquid rises.

The overall effect, a liquid rising in a narrow tube, is called capillarity.

Answer: C. capillarity

Exam tip: If the question describes the rise or fall of liquid in a narrow tube, think "capillary", since "capillary tube" and "capillarity" share the same root. Adhesion and surface tension are the causes, while capillarity is the effect.