DO (dissolved `O_(2)`) of water _________ with an increase in temperature.

Options

A. Decreases
B. Increases
C. Remains constant
D. First increases then decreases

Answer

To answer the question regarding the relationship between dissolved oxygen (DO) in water and temperature, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Dissolved Oxygen (DO)**:
- Dissolved oxygen refers to the amount of oxygen that is present in water, which is essential for aquatic life.

2. **Temperature's Effect on Water**:
- The temperature of water can significantly affect its physical and chemical properties, including its ability to hold dissolved gases.

3. **Cold Water and DO**:
- Cold water has a higher capacity to hold dissolved oxygen. This means that in colder temperatures, the concentration of DO is generally higher.

4. **Warm Water and DO**:
- Conversely, warm water can hold less dissolved oxygen. As the temperature increases, the solubility of oxygen in water decreases, leading to a lower concentration of DO.

5. **Seasonal Variation**:
- In winter or early spring, when temperatures are cooler, the DO levels are higher. In contrast, during summer, as the water warms up, the DO levels decrease.

6. **Conclusion**:
- Therefore, we can conclude that with an increase in temperature, the dissolved oxygen (DO) of water decreases.

### Final Answer:
DO (dissolved O₂) of water **decreases** with an increase in temperature.

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