CHAPTER 18
POLLUTION OF AIR AND WATER
Here is some important points and answer of chapter 18 POLLUTION OF AIR AND WATER NCERT science of class 8 which helps students to better understand the topics of chapter.
Important Points:-
i) Pollution:- The contamination of any natural resources by unwanted substance or impurities is called Pollution.
ii) Global warming:- Increase in the average temperature of the earth due to green house effect and other reason is called Global Warming.
iii) Green house effect:- The availity of the earth's atmosphere to trap and reflect radiation of the sun is called Green house effect.
iv) Air Pollution:- When air got contaminated by impurities is known as Air pollution.
v) Chemical Contimination:- The chemical which are created disturbance in environment are known as Chemical Contimination.
vi) Pollutants:- Particles or substance which creates disturbances in the environment resources such as water, soil,etc are called pollutants.
vii) Portable water:- Water which is safe for drinking is known as Portable Water.
viii) Water Pollution:- Contamination of water by harmful substance is known as Water Pollution.
These are some important points of CHAPTER 18 POLLUTION OF AIR AND WATER of Class 8 Science NCERT.
Here is the answer of textbook Questions of Chapter 18 POLLUTION OF AIR AND WATER .
Ques. 1 What are the different ways in which water gets contaminated?
Ans. Water gets contaminated in the following ways:-
i) Many industries discharge the harmful chemicals into rivers and and streams.
ii) Chemical fertilizers, pesticides and weedicides used in agriculture dissolve in water and seeps into the ground to pollute ground water. They also get washed into the water bodies from the fields.
iii) Throwing of untreated sewage containing disease causing germs directly into the rivers.
iv) Hot water released into water bodies from power plants and industries.
Ques. 2 At an individual level how can you help reduce air Pollution?
Ans. At an individual level,we can do the following things to reduce air Pollution:-
I) Public vehicles should be used instead of private vehicles.
II) CNG and unleaded petrol should be used instead of ordinary petrol and diesel.
III) Create awarness about air pollution by talking to our family members, friends and colony members.
IV) Plants should be planted to reduce the air Pollution and deforestation of trees should be avoided.
Ques.3 Clear transparent water is always fit for drinking. Comment.
Ans. No, water which looks clear and transparent may not be clear and can carry disease causing germs and dissolved impurities. Therefore, such water is not fit for from and has to be purified to make it fit for drinking.
Ques 4. You are a member of the municipal body of your town make a list of measure that would help your town to ensure the supply of clean water to all its residents.
Ans. Some of the measure that would help our town to ensure the supply of clean water to all its residues are as follows:-
I) The water should be purified to make it fit for drinking.
II) The pipes through which water get wasted due to leakage.
III) Chlorine tablets should be supplied to water to kill microscopic organism.
IV) The water tanks used for storing drinking water should be cleaned periodically.
V) The water supply pipes should be away from sewage pipes.
Ques 5. Explain the difference between pure air and polluted air.
Ans. Pure Air
Air is a moisture of gases pure air contains 78% by volume nitrogen, 21% of oxygen and small amount you carbon dioxide,argon ,water vapour,methane, etc. Pure air is good for plants and animals growth.
Polluted Air
Polluted Air contains varied percentage of various gases that are harmful to living organisms. Polluted air is harmful for plants and animals growth.
Ques 6. Explain circumstances leading to acid rain. How does acid rain affect us?
Ans. Pollutants like sulphur dioxide and nitrogen dioxide liberated into the air by industries react with water vapour in air to form sulphuric acid and nitric acid these acids come down as rain called Acid Rain.
Effects of Acid Rain.
i) Acid rain cause direct damage to leaves of plants.
ii) Acid rain cause damage to fresh water life which decrease the fish population in lakes.
iii) Acid Rain damage building and historical monuments.
iv) Acid Rain remove basic nutrients such as Calcium from the soil.
Ques.7. Which of the following is not a green house gas?
a) Carbon dioxide
b)Sulphur dioxide
c) Methane
d) Nitrogen
Ans. Nitrogen
Ques 8. Describe the green house effect in your own word?
Ans. In a nursery,the green house gases trap the sun's heat and heat is not allowed to get out.
Therefore, the green house get warmed up. Similarly the atmosphere on the earth traps the heat of the sun and warms up the surface of the earth. This is called the 'green house effect'. Due to this life was possible on the earth but now it is effecting life as it increase the temperature of the atmosphere,atmospheric gases like CO2 if increased in required percentage, cause the green house effect other gases that cause the green house effect are methane, nitrous oxide, water vapour, etc.
Ques 9. Prepare a brief speech on global warming. You have to deliver the speech in your class.
Soln:
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.
Ques 10. Describe the threat to the beauty of the Taj Mahal.
Soln:
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.
Ques 11.Why does the increased level of nutrients in the water affect the survival of aquatic organisms?
Ans. The fertilizers used in agriculture get dissolved in water bodies from the field. to grow.Nitrates and phosphates in the fertilizer serve as nutrients for the algae to grow.When algae die,they are decomposed by the bacteria they serve as food for bacteria,leading to decrease in oxygen level in water.This effect the survival of the aquatic animal.
This is the complete solution of CHAPTER 18 Pollution Of Air And Water. This is according to latest syllabus of CBSE.
Here's some extra questions are given according to CHAPTER 9 Pollution Of Air An Water of class 8 Science NCERT.
Ques 1.How does boiling purify water?
Ans. Water contains disease causing microbes when water is boiled the micro organism die due to high temperature such water is consider pure and portable water.
Ques 2. Write a short note on Smog?
Ans. Smog is a moisture of fog and smoke and it is formed when oxide of sulphur and nitrogen along with other pollutants combine with fog. Smog is seen as thick fog like layer it causes breathing problems, asthma , wheezing cough, etc.
Ques 3. Why the growth of algae in water bodies is considered a threat to aquatic life?
Ans. Algae grow in water bodies. They increase rapidly in water bodies,that are rich in nutrients washed away from the agriculture fields. When these algae die. They serve as food for bacteria and in the process. The oxygen dissolved in water is used up. The aquatic life is affected due to reduce oxygen levels. Hence the growth of algae in water bodies is considered a threat to aquatic life.
Ques 4. What do you understand by water borne diseases?
Ans. Disease that spread through water are water borne diseases. The carrier or the causative organisms of such diseases breed and spread the disease through water. For example- Cholera, typhoid, jaundice, dengu,amoebiasis ,etc.
These are some extra Questions of Chapter 18 POLLUTION OF AIR AND WATER of class 8 Science NCERT.
FOR ANY QUERY CONTACT US.
RELATED LINK
Comments
Post a Comment
Don't worry,We don't spam.