question_answer

Which of the following statements is false?

A)  The lower the concentration of D.O., the more polluted is the water sample.

B)  The tolerable limit of lead in drinking water is 50 ppb.

C)  Water is considered pure if it has BOD less than 5 ppm.

D)  In COD determination, the pollutants resistant to microbial oxidation are not oxidised by oxidising agents like\[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\].