`BOD` is

Options

A. The amount of oxygen required to convert the NO in to `NO_(2)` in a certain volume of a sample of water.
B. the amount of `F^(-)` ions required to convert, one mole of hydroxypatite into fluorapatite.
C. The amount of oxygen required by bacteria to break down the organic matter present in a certain volume of a sample of water.
D. The amount of oxygen required to break down the non-biodegradable waste.

Answer

### Step-by-Step Solution for the Question: What is BOD?

1. **Definition of BOD**:
BOD stands for Biological Oxygen Demand. It is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water.

2. **Understanding the Concept**:
BOD indicates the level of organic pollution in water. The higher the BOD value, the more polluted the water is, as it means that more oxygen is required by bacteria to decompose the organic material present.

3. **Process Involved**:
BOD is determined by measuring the amount of oxygen consumed by bacteria and other microorganisms when they break down organic matter under aerobic (oxygen-present) conditions.

4. **Conditions for Measurement**:
The measurement of BOD is typically done at a specified temperature, usually 20 degrees Celsius, over a period of 5 days (BOD5).

5. **Importance of BOD**:
BOD is an important parameter in assessing water quality, especially in wastewater treatment, as it helps to determine the effectiveness of the treatment processes and the potential impact on receiving water bodies.

### Summary:
BOD is the measure of the amount of oxygen consumed by bacteria while decomposing organic matter in a water sample, indicating the level of organic pollution.

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