Question

Biochemical Oxygen Deman, (BOD) is a measure of organic material present in water. BOD value less than `5 "ppm"` 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

Correct Answer - A
The total amont of of oxygen consumed by microorganisms (bactoria) in decomposing organic mattr present in certain volume of a sample of water is called Biochemical Oxygen Demand `(BOD)` of the water.
Water considered to be pure if it has BOD less than `5 "ppm"` whears highly polluted water has BOD more than `17"ppm"`
Thus, water having BOD than `5 "ppm"` is rich in dissolved oxygen.