Question

Biochemical oxygen demand (BOD) is a measure of organic material present in water. BOD value less than $5ppm$ indicates a water sample to be

• A. Rich in dissolved oxygen
• B. Poor in dissolved oxygen
• C. Highly polluted
• D. Not suitable for aquatic life

Answer 1

The correct option is A Rich in dissolved oxygen

Clean water has BOD which is less than $5ppm$. If it is equal to or more than $12ppm$, then the water is considered as polluted.

So BOD less than $5ppm$ indicates water to be rich in dissolved oxygen, that helps the microorganisms to oxidize inorganic and organic materials.