Gold number is associated with

Options

A. only lyophobic colloids
B. only lyophilic colloids
C. Both lyophobic and lyophilic colloids
D. None of these

Explanation

**Step-by-Step Solution:**

1. **Understanding Gold Number:**
- The gold number is a term used in colloid chemistry that quantifies the protective power of a colloid. It is defined as the minimum amount of a lyophilic colloid (in milligrams) that must be added to 10 mL of a gold sol to prevent the coagulation of the sol when 1 mL of a 10% NaCl solution is added.

2. **Identifying Lyophilic Colloids:**
- Lyophilic colloids are colloids that have a strong affinity for the solvent. They are stable and do not easily precipitate when electrolytes are added. This stability is crucial for their protective power.

3. **Relation Between Gold Number and Lyophilic Colloids:**
- The gold number specifically measures the effectiveness of lyophilic colloids in stabilizing colloidal solutions against coagulation. A lower gold number indicates a higher protective power.

4. **Conclusion:**
- Therefore, the gold number is associated with lyophilic colloids, as they are the only type of colloids for which the gold number is defined and relevant.

**Final Answer:**
- The gold number is associated with **lyophilic colloids**.

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