Question

Fine soil particles imbibe or absorb water and hold it. This is called as

• A. Percolation
• B. Adhesion
• C. Imbibition
• D. Cohesion

Hint:

Key Exam Tip:
Imbibition is a vital process in soil science and seed germination. Think of it as the "drinking up" of water by dry materials.

Answer 1

The Correct Option is C

The process by which dry soil particles absorb water and swell up is known as imbibition. Imbibition is a special type of diffusion or osmosis where water is absorbed by a solid substance, causing it to increase in volume. In the context of soil, fine soil particles have a large surface area and a porous structure that allows them to readily absorb and retain water. This absorbed water is crucial for plant growth and soil moisture. Let's look at why the other options are incorrect:
• Percolation: This refers to the movement of water through the soil pores under the influence of gravity. It's about water movement, not absorption and retention by the particles themselves.
• Adhesion: This is the attraction between molecules of different substances. While adhesion plays a role in how water sticks to soil particles, it doesn't describe the process of imbibition itself, which is the absorption and swelling.
• Cohesion: This is the attraction between molecules of the same substance. In water, cohesion is responsible for surface tension and the ability of water to form continuous columns. It's not directly related to how soil particles absorb water. Therefore, imbibition is the correct term for the absorption of water by fine soil particles.

Step 1: Analyze the given phenomenon. The question describes fine soil particles taking in and holding water, leading to an increase in their volume (implied by "hold it" and the nature of absorption).

Step 2: Define the given terms.
• Percolation: Downward movement of water through soil.
• Adhesion: Attraction between unlike molecules (e.g., water and soil particles).
• Imbibition: Absorption of water by a solid substance, causing it to swell.
• Cohesion: Attraction between like molecules (e.g., water molecules).

Step 3: Match the phenomenon with the correct definition. The description "imbibe or absorb water and hold it" perfectly matches the definition of imbibition, which often results in swelling. Soil particles, especially fine ones like clay and silt, have hydrophilic surfaces that readily absorb water through imbibition.

Step 4: Eliminate incorrect options. Percolation is about water movement, adhesion and cohesion are intermolecular forces. None of these specifically describe the absorption and retention of water by the solid particles themselves, which is what imbibition does. Final Answer: \(\boxed{\text{Imbibition}}\)