Select the colloidal material in domestic sewage

Options

A. Sand, Slit and Clay
B. Fecal matter, Bacteria, cloth and paper fibres
C. Nitrate, ammonia, phosphate
D. Garbadge.

Answer

### Step-by-Step Solution:

1. **Understanding Domestic Sewage**:
- Domestic sewage refers to the waste materials that are discharged from households and industries. It includes various forms of waste such as solid waste, liquid waste, and other materials that can pollute the environment.

2. **Defining Colloidal Material**:
- Colloidal materials are substances that consist of microscopic particles suspended in another medium. These particles are not fully dissolved and can remain suspended in liquids.

3. **Analyzing the Options**:
- The question provides several options to identify which of them are colloidal materials present in domestic sewage.

4. **Evaluating Each Option**:
- **Option A: Sand, silt, and clay**: These are solid particles that can be suspended in water but are not classified as colloidal materials.
- **Option B: Fecal matter, bacteria, cloth, and paper fibers**: These materials can remain suspended in sewage and are considered colloidal because they do not dissolve completely in water.
- **Option C: Nitrate, ammonia, and phosphate**: These are soluble salts that dissolve in water and are not colloidal materials.
- **Option D: Garbage**: This is a general term for waste and does not specifically refer to colloidal materials.

5. **Conclusion**:
- Based on the evaluation, the correct answer is **Option B: Fecal matter, bacteria, cloth, and paper fibers**, as these are the colloidal materials present in domestic sewage.