The swelling of a gel in water is called……….

Explanation

**Step-by-Step Solution:**

1. **Understanding Gel Structure**: A gel is a colloidal system consisting of a solid dispersed phase and a liquid continuous phase. In this case, the solid is the gel matrix, and the liquid is typically water.

2. **Process of Swelling**: When a gel is placed in water, it absorbs the water due to the difference in concentration between the gel and the surrounding water. The water molecules move into the gel, causing it to swell.

3. **Identifying the Process**: The movement of solvent (water) into the gel occurs due to osmotic pressure. This process is driven by the concentration gradient, where water moves from an area of higher concentration (the water) to an area of lower concentration (the gel).

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