BOD of two samples of water A and B were 120 mg/l and 400 mg/l respectively. Which sample is more polluted.

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Solution

BOD- Biochemical Oxygen Demand is the amount of dissolved oxygen in a water body, required by microorganisms for the aerobic breakdown of organic matter in the water. Higher the value of BOD more is the amount of organic matter available for aerobic bacteria. this corresponds to the greater degree of pollution. Hence, the water sample B that has BOD of 400 mg/l is more polluted than sample B having BOD of 120 mg/l.

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