Lyophilic sols are also called reversible colloids because

Options

A. they can be reformed by mixing residue (dispersed phase) in dispersion medium even after drying
B. they can be easily precipitated from the colloidal system
C. once formed, the disperison medium and dispersed phase cannot be separaed
D. special reversible reactions are used to prepare them.

Answer

**Step-by-Step Solution:**

1. **Understanding Lyophilic Sols:**
- Lyophilic sols are colloidal systems where the dispersed phase (solid) is attracted to the dispersion medium (liquid). They are also known as "liquid-loving" colloids because they have a strong affinity for the liquid phase.

2. **Characteristics of Lyophilic Sols:**
- These sols are stable and can easily be formed by mixing a solid substance (like gum or gelatin) with a suitable liquid.
- The stability of these sols allows them to resist changes in their state under various conditions.

3. **Reversibility of Lyophilic Sols:**
- The term "reversible colloids" refers to the ability of lyophilic sols to be reconstituted after drying.
- When lyophilic sols are dried, they leave behind a residue. This residue can be re-dispersed in the original dispersion medium to recreate the colloidal solution.

4. **Conclusion:**
- Therefore, lyophilic sols are called reversible colloids because they can be reformed by mixing the residue left after drying with the dispersion medium. This characteristic distinguishes them from lyophobic sols, which cannot be easily reconstituted.

**Final Answer:**
Lyophilic sols are called reversible colloids because they can be reformed by mixing the residue in the dispersion medium even after drying.

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