Which of the following is not a negative colloid

Options

A. Acid dye
B. basic dye
C. Platinum
D. All

Answer

To determine which of the following is not a negative colloid, we need to classify the given options based on their charge. Colloids can be either positively charged or negatively charged.

### Step-by-Step Solution:

1. **Understanding Colloids**: Colloids are mixtures where tiny particles are dispersed throughout another substance. They can be classified based on the charge of the dispersed particles.

2. **Identifying Negative Colloids**: Negative colloids typically include metal sols (like gold (Au), silver (Ag), copper (Cu), platinum (Pt)), metal sulfides (like As2S3, CdS), and certain dyes (like Congo Red).

3. **Identifying Positive Colloids**: Positive colloids include metallic hydroxides (like Fe(OH)3, Al(OH)3, Cr(OH)3) and basic dyes (like Methylene Blue).

4. **Analyzing the Options**:
- If the options include a basic dye, it is known to be positively charged.
- If the options include a metal sol or dye like Congo Red, it is negatively charged.

5. **Conclusion**: Based on the classification, if one of the options is a basic dye, it is not a negative colloid. Therefore, the correct answer is the basic dye.

### Final Answer:
The option that is not a negative colloid is **Basic Dye**.