(a)Give the importance of measuring BOD of a water body (b) What is desirable concentration of fluoride ion pH of drinking water? (c) Give the harmful effect of nitrogen dioxide.
(a) BOD is a measure of level of pollution caused by organic biodegradable material. Low value of BOD means water is less polluted. (b) 1 ppm is desirable concentration of fluoride ions in drinking water. The pH of drinking water should be between 5.5 (c) Nitrogen dioxide is extremely toxic to living tissues and harmful to plants, paints, and metals. It causes acid rain. It produces photochemical smog.
