NCERT solution for class 8 || Science || Chapter 18 - Pollution of air and water

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NCERT solution for class 8 ||   Science ||  Chapter 18 - Pollution of air and water

Chapter 18 - Pollution of air and water 

Exercise 

Q1. What are the different ways in which water gets contaminated ?

Answer - The different ways in which water gets contaminated aur 

  • Domestic sewage , 
  • Agriculture chemicals fertilizers and pesticides 
  •  Industrial waste  like chemical waste solid waste liquid waste etc

Q2. At an individual level how can you help reduce air pollution ? 

Answer - I do following changes in My lifestyle to reduce air pollution 

  • Planting more and more trees around surrounding 
  • I will not use vehicles for short distance 
  • Use public transport as possible as 

Q3. Clear transparent water is always fit for drinking comment ? 

Answer - Clear transparent water does not shows any type of impurities but it may possible microorganism present inside it so it is not  fit for drinking

Q4. You are a member of a municipal body of your town make a list of measures that would help you are town to ensure the supply of clean water to all its residents? 

Answer. -  

  • Clean the water tank time to time 
  • Use chlorine tablets for cleaning of water  
  • Taking care of the sewage pipe line and water pipeline not be mixed. 

Q5. Explain the difference between pure air and polluted air? 

Answer -  

Pure Air 

1 Pure air contains 78% of nitrogen 21% of oxygen 0.03% of carbon dai oxide and the other gases are in very small amount 

2. It does not contain any type of dust particle smoke ,fog and unwanted impurities 

Polluted Air 

1. Polluted air contain the the compounds like nitrogen oxide carbon dioxide Sulphur dioxide all these are the harmful gases 

2. Polluted air also contain then lots of dust particles smoke and fog

Q6. Explain circumstances leading to acid rain how does acid rain affect us ? 

Answer -  Atmospheric Nitrogen dioxide and Sulphur dioxide combines with atmospheric water vapour and from sulfuric acid and nitric acid these acid comes down with rain and make the rain acidic 

Effect of the acid rain 

  • Acid rain destroy the vegetation 
  • It may shows the bad effect on the living organism 
  • Metal things are corroded when come in contact with acid rain  
  • It effect on the buildings and historical monuments. 

Q7. Which of the following is not a greenhouse gas 

a) Carbon dioxide 

b) Sulphur dioxide 

c) Methane 

d)  Nitrogen  

Answer -  Nitrogen 

Q8. Describe the greenhouse effect in your own words ? 

Answer - Greenhouse effect maintain the hotness of atmosphere. In Sun energy comes down on the earth surface then some part is absorbed by Earth while the remaining part is reflected by it but some greenhouse gases like carbon dioxide carbon monoxide trap these  heat energy and maintain the atmosphere warm this is good for living being . But if it is causes in extra quantity then it may lead to global warming And it is harmful for life

Q9. Prepare a brief speech on global warming you have to deliver the speech in your class ? 

Answer - 

Good morning to all my teachers and my dear friends 

,Today I want to deliver few words in front of you on  global warming

 Global warming is the increasing of atmospheric temperature. It can causes due to increases the greenhouse gas inside the atmosphere . Greenhouse gases are trap the heat energy reflected by the Earth surface and keep it inside the atmosphere and make the atmosphere warm but if the quantity of greenhouse gases increases then the heat energy trapped by them also increases and it may cause global warming which is harmful for animal plants and their life

Q10. Describe the threat to the beauty of the Taj Mahal ? 

Answer -Taj Mahal is the seventh wonder of world it is made up of white marble. It is located near to the Mathura but Mathura is the industrial area and due to air pollution the acid rain causes in that area. Also the smoke particles arises from the industries are suspended on the marbles and leaves a yellow spot on that marbles 

So it loses the  beauty of Taj Mahal

Q11. Why does the increased level of nutrients in the water affect the survival of aquatic organisms ?  

Answer- Increased level of nutrients in the water affects the survival of aquatic organisms because these are become a nutrient for the algae after the death of the algae their bodies are decomposers by microorganisms and the oxygen available used for the process of decomposition it may decrease the oxygen in water and it is affected for aquatic animal. 



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