Water above the dissolved `O_(2)` content may be considered uncontaminated

Options

A. 0.8 mg/l
B. 0.009 mg/l
C. 8.0 mg/l
D. `8 mug`/l

Answer

To determine the level of dissolved oxygen content in water that indicates it is uncontaminated, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Dissolved Oxygen (DO):**
- Dissolved oxygen is crucial for aquatic life. It is the oxygen that is present in water and is necessary for the survival of fish and other aquatic organisms.

2. **Identifying Contamination Levels:**
- Water with low levels of dissolved oxygen indicates contamination. Specifically, levels below 5 milligrams per liter (mg/L) are considered contaminated and not suitable for human consumption.

3. **Determining Uncontaminated Levels:**
- Water that has a higher concentration of dissolved oxygen is considered to be of better quality. Generally, water with more than 8 mg/L of dissolved oxygen is deemed uncontaminated.

4. **Evaluating the Options:**
- The options provided are:
- 0.8 mg/L
- 0.009 mg/L
- 8 mg/L
- 8 micrograms/L (which is equivalent to 0.008 mg/L)
- Among these, only 8 mg/L meets the criteria for being classified as uncontaminated.

5. **Conclusion:**
- Therefore, the correct answer is that water with a dissolved oxygen content above 8 mg/L is considered uncontaminated.

### Final Answer:
The correct option is **8 milligrams per liter (8 mg/L)**.

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