Chemical treatment of surface water can be carried out by the addition of

Options

A. bleaching power
B. alum
C. oxygen
D. carbon dioxide

Explanation

To solve the question regarding the chemical treatment of surface water, we need to analyze the options provided and determine which one is suitable for this purpose.

### Step-by-Step Solution:

1. **Understanding Surface Water Treatment**:
- Surface water, such as water from rivers and lakes, often contains impurities and pathogens. To make it safe for drinking, it needs to be treated chemically.

2. **Evaluating the Options**:
- **Option 1: Bleaching Powder (Calcium Hypochlorite)**: This compound contains chlorine, which is a strong disinfectant. It is commonly used to kill bacteria and other pathogens in water.
- **Option 2: Alum (Aluminum Sulfate)**: Alum is primarily used as a coagulant to help remove suspended particles from water, but it does not disinfect.
- **Option 3: Oxygen**: While oxygen is essential for aquatic life, it does not have disinfectant properties and is not used for treating water.
- **Option 4: Carbon Dioxide**: This gas is not used for disinfecting or treating water and does not help in removing impurities.

3. **Conclusion**:
- Based on the evaluation, the most effective chemical for treating surface water to ensure it is safe for consumption is **Bleaching Powder**. Therefore, the answer is **Option 1: Bleaching Powder**.

### Final Answer:
The chemical treatment of surface water can be carried out by the addition of **Bleaching Powder**.

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