Silica gel (Keieselghur)/Diatomite/Diatomaceous earth is obtained by-

Options

A. Diatoms
B. Dinoflagellates
C. Euglenoids
D. Brown algae

Answer

To answer the question about how silica gel (Keiselghur) is obtained, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Source**: Silica gel is derived from diatomaceous earth, which is primarily composed of the fossilized remains of diatoms.

2. **Identifying Diatoms**: Diatoms are a class of microalgae known for their unique silica cell walls. They belong to the class Bacillariophyceae.

3. **Extraction Process**: The process of obtaining silica gel involves several steps:
- **Extraction**: Diatomaceous earth is extracted from natural deposits.
- **Grinding**: The extracted material is then ground into a fine powder.
- **Sieving**: The ground material is sieved to obtain the desired particle size.

4. **Application**: Silica gel is commonly used in filtration techniques due to its porous nature.

5. **Conclusion**: Based on the above information, the correct answer to the question is that silica gel is obtained from diatoms.

### Final Answer:
Silica gel (Keiselghur) is obtained from **diatoms**.

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