Dissolved oxygen present in natural water has

Options

A. 4-6 ppm
B. 10-20 ppm
C. 40-60 ppm
D. 80-100 ppm

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks about the amount of dissolved oxygen present in natural water. Natural water typically refers to water found in rivers, lakes, and oceans, which has a pH value around 7.

2. **Defining Dissolved Oxygen**: Dissolved oxygen (DO) refers to the oxygen that is present in water in a molecular form, which is available for aquatic organisms to breathe. It is important to note that the oxygen that is part of the water molecule (H2O) is not considered dissolved oxygen.

3. **Sources of Dissolved Oxygen**: Dissolved oxygen in natural water comes from various sources, including the atmosphere (air) and photosynthesis from aquatic plants. Water has the ability to dissolve gases from the environment, which contributes to the presence of dissolved oxygen.

4. **Quantifying Dissolved Oxygen**: In natural water, the typical concentration of dissolved oxygen is measured in parts per million (ppm). For natural water with a pH of around 7, the concentration of dissolved oxygen is generally found to be between 4 to 6 ppm.

5. **Conclusion**: Therefore, the answer to the question regarding the amount of dissolved oxygen present in natural water is that it ranges from 4 to 6 ppm.

**Final Answer**: The dissolved oxygen present in natural water is 4 to 6 ppm.

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