Q. Which one of the following statements is not true?
A) Oxides of sulphur, nitrogen and carbon are the most widespread air pollutant
B) pH of drinking water should be between 5.5 – 9.5
C) Concentration of DO below 6 ppm is good for the growth of fish
D) Clean water would have a BOD value of less than 5 ppm
Explanation
[Solution from source] Fish need dissolved oxygen of about 6 ppm or more; DO below 6 ppm suppresses their growth, so calling it good is false. Clean water has BOD below 5 ppm, and oxides of S, N and C are the most widespread air pollutants. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.