Gold number gives

Options

A. The amount of gold present in the sol
B. The amount of gold required to break the sol
C. The amount of gold required to protect the lyophobic sol
D. None of the above

Answer

### Step-by-Step Solution:

1. **Understanding Gold Number**:
- The gold number is a measure of the effectiveness of a protective colloid in preventing the precipitation of a colloidal solution. It quantifies how much protective colloid is needed to stabilize a colloid.

2. **Definition of Gold Number**:
- The gold number is defined as the number of milligrams of a protective colloid required to prevent the precipitation of 10 cc of a gold sol when 10% sodium chloride solution is added.

3. **Types of Colloids**:
- There are two types of colloids: lyophilic (solvent-loving) and lyophobic (solvent-fearing). The protective colloid is typically lyophilic, which coats the lyophobic particles to stabilize them.

4. **Analyzing the Options**:
- **Option A**: "Amount of gold present in the sol" - This is incorrect as the gold number does not measure the amount of gold.
- **Option B**: "Amount of gold required to break the sol" - This is also incorrect since the gold number is about protection, not breaking.
- **Option C**: "Amount of gold required to protect the lyophobic colloid" - This is misleading; it refers to the protective colloid, not gold itself.
- **Option D**: "None of the above" - This is correct as none of the previous options accurately describe what the gold number represents.

5. **Conclusion**:
- Therefore, the correct answer is **Option D: None of the above**.