Select the positive sol in the following

Options

A. `Al(OH)_(3)` sol
B. Gold sol
C. CdS sol
D. Gum

Answer

To identify the positive sol from the given options, we will follow these steps:

### Step 1: Understand the Classification of Sols
Sols can be categorized into two types based on the charge of their fixed layer:
- **Positive Sols**: These sols have a positive charge and typically include hydrated metallic oxides, basic dyes, and certain biological components.
- **Negative Sols**: These sols have a negative charge and include metallic sols, metallic sulfides, acidic dyes, and certain organic components.

### Step 2: Identify Examples of Positive Sols
Common examples of positive sols include:
- Hydrated metallic oxides (e.g., Al₂O₃·xH₂O, Fe₂O₃·xH₂O)
- Basic dyes (e.g., Methylene blue)
- Biological components (e.g., Hemoglobin)
- Certain metal oxides (e.g., TiO₂)

### Step 3: Analyze the Given Options
We need to look at the options provided in the question and determine which one fits the criteria for a positive sol.

1. **Hydrated Metallic Oxides**: These are positively charged. For example, Al(OH)₃ is a hydrated form of Al₂O₃ and thus is a positive sol.
2. **Basic Dyes**: Examples like Methylene blue are also positive.
3. **Hemoglobin**: This is a biological component that is positively charged.
4. **Metallic Sols**: Such as gold, silver, and copper sols, which are negatively charged.
5. **Metallic Sulfides**: These are also negatively charged.
6. **Acidic Dyes**: These are negatively charged.
7. **Organic Components**: Such as starch and gelatin, which are negatively charged.

### Step 4: Conclusion
From the analysis, we find that the only option that represents a positive sol is the hydrated metallic oxide, specifically Al(OH)₃. Therefore, the answer to the question is:

**Answer: Al(OH)₃ (Hydrated Metallic Oxide)**

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