Measuring Biochemical Oxygen Demand (BOD) is a method used for

Options

A. Working out the efficiency of oil driven automobile engines
B. Measuring the activity of Saccharomyces cerevisae in producing curd on a commerical scale
C. Working out the efficiency of R.B.Cs about their capacity to carry oxygen
D. Estimating the amount the organic meter in sewage water

Answer

**Step-by-Step Solution:**

1. **Understanding BOD**:
- BOD stands for Biochemical Oxygen Demand. It is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water.
- It indicates the level of organic pollution in water bodies.

2. **Purpose of Measuring BOD**:
- BOD is primarily used to assess the degree of pollution in water bodies, particularly from organic waste.
- It helps in determining the efficiency of wastewater treatment processes.

3. **Normal BOD Levels**:
- In clean water, BOD levels are typically low (around 1-5 mg/L).
- Moderate pollution shows BOD levels between 5-20 mg/L.
- High pollution levels can exceed 20 mg/L, indicating significant organic waste.

4. **Analyzing the Options**:
- **Option A**: Working out the efficiency of oil-driven automobile engines - Incorrect, as BOD is unrelated to engine efficiency.
- **Option B**: Measuring the activity of Saccharomyces curvatus in producing curd - Incorrect, as this is related to fermentation, not organic waste measurement.
- **Option C**: Working out the efficiency of RBC to carry oxygen - Incorrect, as this pertains to blood physiology, not BOD.
- **Option D**: Estimating the amount of organic matter present in seawater - Correct, as BOD measures the organic matter in water.

5. **Conclusion**:
- The correct answer is **Option D**, which states that BOD is used for estimating the amount of organic matter present in seawater.