Which one of the followings is an indirect measure of the organic matter present in water?

BOD

The correct answer is Option (4) → BOD

Explanation:

• BOD (Biological Oxygen Demand) → Measures how much oxygen is consumed by microorganisms while decomposing organic matter in water.
• Higher BOD = more organic pollution.
• It is an indirect measure of organic matter.
• pH level → Indicates acidity/alkalinity, not organic matter.
• Nitrogen content → Shows nutrient level, but not direct measure of organic matter.
• Turbidity → Measures suspended particles (silt, clay, microbes), not organic matter specifically.