Which of the following is not a compound ?

Options

A. Black lead
B. White lead
C. Red lead
D. None

Explanation

To determine which of the following substances is not a compound, we will analyze each option provided.

1. **Identify the Options**: We have four options to consider:
- Option 1: Black lead
- Option 2: White lead
- Option 3: Red lead
- Option 4: None

2. **Analyze Each Option**:
- **Black Lead**: Black lead is another name for graphite. Graphite is a form of carbon and does not have a fixed chemical formula like a compound. Therefore, it is not considered a compound.
- **White Lead**: White lead is known as basic lead carbonate, which has the formula \( \text{PbCO}_3 \cdot \text{Pb(OH)}_2 \). This is a compound because it consists of lead, carbon, and oxygen in a fixed ratio.
- **Red Lead**: Red lead, or lead tetroxide, has the chemical formula \( \text{Pb}_3\text{O}_4 \). This is also a compound as it contains lead and oxygen in a specific ratio.
- **None**: This option implies that all the given substances are compounds, which is incorrect based on our analysis.

3. **Conclusion**: Based on the analysis, the substance that is not a compound is **Black Lead** (Option 1).

Therefore, the correct answer is **Option 1: Black Lead**.