NEET2013ChemistryEnvironmental ChemistryActual
Which one of following statements is not true?
Options
- AClean water would have a BOD value of 5 ppm
- BFluoride deficiency in drinking water is harmful. Soluble fluoride is often used to bring its concentration up
- CWhen the pH of rain water is higher than 6.5 , it is called acid rain
- DDissolved Oxygen (DO) in cold water can reach a concentration upto 10 ppm
Correct answer
C. When the pH of rain water is higher than 6.5 , it is called acid rain
Step-by-step solution
The acid rain happens when the pH of the water drops below 5.6. Related Theory The oxides of N ₂, C and S mix with water during the precipitation. Non-metal axide + H ₂ O Acid Thus the pH of water decreases and acid rain is formed.