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Which one of the following statements is not true?
A
Oxides of sulphur, nitrogen and carbon are the most widespread air pollutants
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
Detailed Solution
Oxides of sulphur, nitrogen and carbon are the most widespread gaseous air pollutants (true).
The pH of drinking water should be between 5.5 and 9.5 (true).
Clean water has a BOD value of less than 5 ppm, while highly polluted water may have a BOD of 17 ppm or more (true).
Dissolved oxygen (DO) is essential for aquatic life; if the concentration of DO falls below 6 ppm, the growth of fish is inhibited.
So the statement that DO below 6 ppm is good for the growth of fish is not true.
The pH of drinking water should be between 5.5 and 9.5 (true).
Clean water has a BOD value of less than 5 ppm, while highly polluted water may have a BOD of 17 ppm or more (true).
Dissolved oxygen (DO) is essential for aquatic life; if the concentration of DO falls below 6 ppm, the growth of fish is inhibited.
So the statement that DO below 6 ppm is good for the growth of fish is not true.