Q. Select the incorrect statement.
A) Water is considered pure if it has BOD less than 5 ppm
B) In COD determination, the pollutants resistant to microbial oxidation are not oxidised by oxidising agent like $K_{2}Cr_{2}O_{7}$
C) The lower the concentration of DO, the more polluted is the water sample
D) The tolerable limit of lead in drinking water is 50 ppm
Explanation
(b)
In COD determination, the pollutants, which are resistant to microbial oxidation, are also oxidised by strong oxidising agents such as $K_{2}Cr_{2}O_{7}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.