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Science Give Scientific Reason.

Pollution · Maharashtra Board STD 8 (MSBSHSE - Semi English Medium). 4 questions.

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Give Scientific Reason.

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4 questions · timed · auto-graded

Question 13 Marks
A hole has been observed in the ozone layer in the stratosphere near Antarctica.
Answer
  1. Ozone layer depletion is mainly caused due to the action of CFC (Chlorofluorocarbon) molecules in the air.
  2. Due to various increased activities of humans, the magnitude of air pollution has been increasing in the last few decades.
  3. CFC molecules were used as coolants in refrigerators, freezers and air conditioners.
  4. They were also present in industrial solvents, dry cleaning agents and hospital sterilants, aerosols and foam. Due to such enhanced use, much of the CFCs were liberated in the last few years.
  5. CFC molecules are decomposed by ultraviolet rays which release chlorine and fluorine molecules.
  6. Chlorine and fluorine react with the ozone resulting in a hole in the ozone layer present in the stratosphere.

Therefore, a hole has been observed in the ozone layer in the stratosphere above Antarctica.

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Question 23 Marks
Due to agriculture, there can be a lot of air pollution.
Answer
1. During agricultural practices, open field burning is done. Due to this burning there is emission of gases like $SO _2, CO _2, CH _4, CO$ and oxides of nitrogen along with large amounts of particulate matter.
2. In agricultural practices, pesticides used emit toxic chemicals.
3. Industrial farms pollute air by emitting foul odour and airborne pollutants.
4. When manure is decomposed, there is production of greenhouse gases.
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Question 33 Marks
Use public transport instead of private vehicles.
Answer
  1. All the automobiles use fossil used to soften the water. fuels Burning of fossil fuels causes air pollution by gaseous pollutants as well as by particulates.
  2. Toxic gases such as $CO , CH _4, SO _2$, etc. are emitted through automobile exhausts.
  3. When each person uses private vehicles, the proportion of air pollution increases.
  4. Instead, public transport helps to reduce air pollution it will also help to ease trafficams.
  5. Therefore, as a role of citizen in pollution control, public transport should be used instead of private vehicles.
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Question 43 Marks
Domestic sewage is harmful for all forms of life.
Answer
  1. Domestic sewage contains water
  2. There are detergents and washing private vehicles. powders containing phosphate, which are used to soften the water.
  3. These chemicals are harmful to aquatic animals.
  4. They also contain disease. causing pathogenic bacteria and viruses.
  5. Hence, domestic sewage is harmful for originating from kitchen, bathrooms, toilet, forms of
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Give Scientific Reason. - Science STD 8 Questions - Vidyadip