Which of the following is positively charged colloidal particle ?

Options

A. `As_(2)S_(3)`
B. `Al_(2) O_(3) . xH_(2)O`
C. Au
D. Pt

Answer

To determine which of the following is a positively charged colloidal particle, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Colloidal Particles**:
- Colloidal particles can carry either a positive or negative charge. The charge of the colloidal particles influences their stability and behavior in a solution.

2. **Identify Common Types of Positively Charged Colloidal Particles**:
- Positively charged colloidal particles typically include:
- Hydrated metallic oxides (e.g., Al₂O₃·xH₂O, CrO₃·xH₂O)
- Basic dyes (e.g., methylene blue)
- Certain metallic oxides (e.g., TiO₂)

3. **Identify Common Types of Negatively Charged Colloidal Particles**:
- Negatively charged colloidal particles often include:
- Metallic salts (e.g., copper salts, silver salts)
- Metallic sulfides (e.g., arsenic sulfide, antimony sulfide)
- Acidic dyes (e.g., eosin, Congo red)
- Organic colloids (e.g., starch, gums, gelatin)

4. **Analyze the Given Options**:
- If the options provided include substances like hydrated metallic oxides, basic dyes, or certain metallic oxides, these would likely be positively charged.
- If the options include metallic salts or sulfides, these would be negatively charged.

5. **Select the Correct Answer**:
- Based on the identification of positively charged colloidal particles, we can conclude that the correct answer is the option that includes a hydrated metallic oxide, a basic dye, or a similar positively charged colloidal substance.

### Conclusion:
- After analyzing the options, the positively charged colloidal particle is identified as **option B**, which corresponds to a hydrated metallic oxide or a basic dye.