Pick from the following one chemical used to disinfect water.

Options

A. Chlorine
B. Washing soda
C. Silica
D. Coal

Answer

**Step-by-Step Solution:**

1. **Understand the Question**: The question asks for one chemical used to disinfect water.

2. **Review the Options**: The options provided are:
- Chlorine
- Washing soda
- Silica
- Coal

3. **Identify the Purpose of Disinfection**: Disinfection is the process of eliminating harmful microorganisms from water before it is discharged into the environment.

4. **Recall Information from the Transcript**: The transcript mentions that chlorine is a chemical used for disinfecting water in wastewater treatment plants. It is specifically noted as a chemical that helps eliminate harmful microorganisms.

5. **Select the Correct Answer**: Based on the information, the correct chemical used to disinfect water is **Chlorine**.

**Final Answer**: Chlorine

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