Environmental Chemistry - Result Question 9
####10. Which one of the following statements is not true?
[NEET Kar: 2013]
(a) Dissolved oxygen (DO) in cold water can reach a concentration upto $10 ppm$.
(b) Clean water would have a BOD value of 5 ppm. (c) Fluoride deficiency in drinking water is harmful. Soluble fluoride is often used to bring its concentration upto $1 ppm$.
(d) When the $pH$ of rain water is higher than 6.5, it is called acid rain.
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Solution:
- (d) Acid rain is the rain water containing sulphuric acid and nitric acid which are formed from the oxides of sulphur and nitrogen present in the air as pollutants. Rain water has a $pH$ below 5.6.
