Which of the following conditions shows the polluted environment.

1.	Which of the following conditions shows the polluted environment.
Answer» pH of rain water is 5.6. amount of CARBONDIOXIDE in the atmosphere is 0.03%. biochemical oxygen demand eutrophication Solution :Polluted water may contain nutrients for the growth of algae. It covers the water surface and reduces the oxygen concentration in water. This leads to accumulation of obnoxious DECAY anaerobic condition and animal death. This process is known as eutrophication. The amount of oxygen required by BACTERIA to break the organic matter present in a certain volume of sample of water is known as Biochemical Oxygen Demand. Clean water would have BOD value of 5 ppm whereas highly polluted could have BOD value of 17 ppm or more. Normally rain water has pH of 6. When water reacts with carbon dioxide in the atmosphere `H^+` on formed. When the pH of the rain water drops below 5.6, it is called acid rain.

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