Diatomaceous earth is used for all except-

Options

A. Polishing
B. Filteration of oils and syrups
C. Sound and fire proof room
D. Biogas

Answer

### Step-by-Step Solution:

1. **Understanding Diatomaceous Earth**: Diatomaceous earth is formed from the fossilized remains of diatoms, which are a type of algae. The cell walls of diatoms are made of silica, making them very durable and useful in various applications.

2. **Identifying Uses of Diatomaceous Earth**:
- **Polishing**: Diatomaceous earth is commonly used as a polishing agent due to its fine, abrasive nature.
- **Filtration**: It is also used in the filtration of oils and syrups, as its porous structure allows it to effectively filter out impurities.
- **Sound and Fireproof Rooms**: Diatomaceous earth can be used in soundproofing and fireproofing materials due to its insulating properties.

3. **Analyzing the Options**:
- **Option A (Polishing)**: Diatomaceous earth is used for polishing.
- **Option B (Filtration of oils and syrup)**: Diatomaceous earth is used for filtration.
- **Option C (Sound and fireproof room)**: Diatomaceous earth is used in sound and fireproof rooms.
- **Option D (Biohaze)**: There is no significant use of diatomaceous earth in biogas production or biohaze applications.

4. **Conclusion**: Since diatomaceous earth is not used in the context of biogas or biohaze, the correct answer is **Option D**.

### Final Answer:
D) Biohaze

---