NCERT Solutions For Class 8 Science Chapter 18 Pollution of Air and Water

Class 8 Science Chapter 18 Pollution of Air and Water

NCERT Solutions For Class 8 Science Chapter 18 Pollution Of Air And Water, (Science) exam are Students are taught thru NCERT books in some of state board and CBSE Schools.  As the chapter involves an end, there is an exercise provided to assist students prepare for evaluation.  Students need to clear up those exercises very well because the questions withinside the very last asked from those. 

Sometimes, students get stuck withinside the exercises and are not able to clear up all of the questions.  To assist students solve all of the questions and maintain their studies without a doubt, we have provided step by step NCERT Solutions for the students for all classes.  These answers will similarly help students in scoring better marks with the assist of properly illustrated Solutions as a way to similarly assist the students and answering the questions right.

NCERT Solutions For Class 8 Science Chapter 18 Pollution of Air and Water

Class 8 Science Chapter 18 Pollution of Air and Water

Exercise Questions

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


The different ways in which the water gets contaminated are:

i) Industrial waste: The harmful chemical wastes get released by the industries into water sources.

ii) Sewage waste: kitchen, laundry and toilets release the waste materials and this pollutes water.

iii) Agricultural chemicals: Excessive amount of pesticides and fertilizers are used by the farmers for enhancing crop production. Rains and floods carry these harmful chemicals to water bodies, which results in water pollution.

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


The following are the steps we can take for reduction of air pollution:

i) We should avoid the usage of personal cars and opt for public transport as much as possible.

ii) We should properly dispose of the garbage and not burn it.

iii) For shorter distances, avoid vehicles.

iv) We should control the number of emissions from household chimneys and vehicles.

v) We should replace our vehicle fuel, diesel and petrol by LPG and CNG.

3. Clear, transparent water is always fit for drinking. Comment.


No, we don’t agree to the statement that clean water is always fit for drinking because water might appear clean but it may contain some disease-causing micro-organisms and several other dissolved impurities. Hence, we advise purifying the water by boiling or by any purifying system before drinking it.

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


The following are the measures taken by us to ensure the supply of clean water to our town residents:

a) We clean the area around the water pipes.

b) The main water source has to be built in a clean surrounding and should be maintained properly.

c) Chemical methods such as chlorination must be used for purifying water.

5. Explain the differences between pure air and polluted air.


The composition of pure air contains 78% nitrogen, 21% oxygen and 0.03% carbon dioxide. Besides these, there are some other gases like methane, argon, ozone and water vapors’. The air is said to be polluted when the composition of air is altered by the addition of harmful substances or gases such as sulphur dioxide, carbon monoxide, nitrogen dioxide and particulate matter.

6. Explain circumstances leading to acid rain. How does acid rain affect us?


Sulphur dioxide and nitrogen dioxide are the type of pollutants, which are released into the atmosphere by the burning of fossil fuels like diesel and coal. These pollutants react with the water vapours present in the atmosphere to form nitric acid and sulphuric acid, respectively. By precipitation, these acids come down and form the acid rain.

Effects caused by the acid rain:

a) It destroys the crops.

b) Harmful for the building especially to those made of white marble like the Taj Mahal.

7. Which of the following is not a greenhouse gas?

(a) Carbon dioxide

(b) Sulphur dioxide

(c) Methane

(d) Nitrogen


Answer is (d) Nitrogen

8. Describe the ‘Green House Effect’ in your own words.


The greenhouse effect is the cause of global warming, i.e. overall increase in the temperature of the Earth. The greenhouse gases cause the greenhouse effect. Examples of greenhouses gases include methane, CO2 and water vapour. When solar radiation reaches the Earth, some radiations are absorbed by the Earth and then released back to the atmosphere. Greenhouse gases present into the atmosphere trap these radiations and do not allow the heat to leave. This helps our planet in keeping warm and thus helps in human survival. However, an indiscriminate increase in level of greenhouse gases, it can lead to an excessive increase in the Earth’s temperature leading to global warming.

9. Prepare a brief speech on global warming. You have to deliver the speech in your class.


The increase in the average temperature of the Earth’s surface is known as global warming. It occurs due to the increased concentration of greenhouse gases in the atmosphere. The greenhouse gases include methane, CO2, and water vapour. These gases trap the solar radiations released back by the earth, which results in keeping our planet warm and helps in human survival. However, an increase in these gases can lead to an increase in the earth temperature resulting in global warming.

10. Describe the threat to the beauty of the Taj Mahal.


The major threat to the Taj Mahal is the acid rain. When the acid rain falls on the Taj, which is completely made of marble, they react with marble to form a powder like substance which is then washed away by the rain.  This phenomenon is known as marble cancer. In addition, the soot particles emitted from the Mathura oil refinery located near Agra is leading to the yellowing of Taj Mahal marble.

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


An increase in the level of nutrients in water body leads to an excessive increase in the population of algae in the water body. When these algae die, they serve as food for decomposers. A lot of oxygen is utilized in this process, consequently leading to a decrease in the level of oxygen dissolved in the water body. This, in turn, causes fishes and aquatic organisms to die.

Benefits of NCERT Solutions for Class 8

NCERT Solutions for Class 8 contains extremely important points, and for each chapter, each concept has been simplified to make it easier to remember and increase your chances of achieving excellent exam results. Exam Preparation References Here are some tips on how these Solutions can help you prepare for the exam.

  1. This helps students solve many of the problems in each chapter and encourages them to make their concepts more meaningful.
  2. NCERT Solutions for Class 8 encourage you to update your knowledge and refine your concepts so that you can get good results in the exam.
  3. These NCERT Solutions For Class 8 are the best exam materials, allowing you to learn more about your week and your strengths. To get good results in the exam, it is important to overcome your weaknesses.
  4. Most of the questions in the exam are formulated in a similar way to NCERT textbooks. Therefore, students should review the Solutions in each chapter in order to better understand the topic.
  5. It is free of cost.

Tips & Strategies for Class 8 Exam Preparation

  1. Plan your course and syllabus and make time for revision
  2. Please refer to the NCERT Solutions available on the cbsestudyguru website to clarify your concepts every time you prepare for the exam.
  3. Use the cbsestudyguru learning app to start learning to successfully pass the exam. Provide complete teaching materials, including resolved and unresolved tasks.
  4. It is important to clear all your doubts before the exam with your teachers or Alex (an Al study Bot). 
  5. When you read or study a chapter, write down algorithm formulas, theorems, etc., and review them quickly before the exam.
  6. Practice an ample number of question papers to make your concepts stronger. 
  7. Take rest and a proper meal.  Don’t stress too much. 

Why opt for cbsestudyguru NCERT Solutions for Class 8 ? 

  • cbsestudyguru provide NCERT Solutions for all subjects at your fingertips.
  • These Solutions are designed by subject matter experts and provide Solutions to every NCERT textbook questions. 
  • cbsestudyguru especially focuses on making learning interactive, effective and for all classes.
  • We provide free NCERT Solutions for class 8 and all other classes.

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