The water pollution in river is measured by the dissolved amount of:
✓ Correct answer: d) Oxygen
ExplanationWater pollution in rivers is primarily measured by the Dissolved Oxygen (DO) level, which indicates the amount of oxygen available for aquatic organisms.A low DO level signifies high pollution, as pollutants like organic waste decompose and consume oxygen, making the water uninhabitable for aquatic life.BOD (Biochemical Oxygen Demand) is the amount of oxygen required by microorganisms to decompose organic matter in water over a specific period (usually 5 days at 20°C).High BOD indicates organic pollution, such as from sewage or agricultural runoff, while low BOD signifies cleaner water.COD (Chemical Oxygen Demand) is the total amount of oxygen required to chemically oxidize both organic and inorganic matter in water.COD provides a broader measure of pollution than BOD, including oxygen demand from inorganic substances.369
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