It is defined as the change in the normal properties of water by the presence of foreign material. Water has a property to dissolve a large number of substances. This property is a major causes of pollution It can also be defines as Water pollution may be defined as the addition of inorganic, organic or other harmful substances, which alter the quality of water so that it becomes harmful to man and other organisms.
Water Pollutants : The substances that contaminate or pollute water are called water pollutants. The presence of pollutants can be recognized by the following :
1. Bad taste of drinking water.
2. Offensive odour from lakes, rivers and ocean beaches.
3. Unchecked growth of aquatic weeds in water bodies.
4. Decrease in number of fish in fresh water, river water, sea water, etc.
5. Oil and grease floating on water surface.
A sudden build-up of Water Pollution : When some industrial accidents take place, then there is a sudden build-up of pollution in the environment.
B. O. D. test or biological oxygen demand test is made for measuring _________________ | |||
Right Option : B | |||
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Choose the false answer from the statements given below: | |||
Right Option : B | |||
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Which of the following are correct : (a) Sewage should not be released directly into rivers or lakes. They should be properly treated in sewage treatment plants. (b) Harmful chemicals should not be dumped into water bodies. They should be transformed into some useful substances. | |||
Right Option : C | |||
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