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CBSE Class 08 Science Revision Notes Chapter – 18 Pollution of Air and Water Pollution: An undesirable change in the physical, chemical or biological characteristics of air, water and land that may be harmful to human life and other animals, living conditions, industrial processes and cultural assets. Pollutants: The agents that pollute our environment are called pollutants. Pollutants are the substances which contaminate air, water and land. For eg. smoke ,dust,fog and gases like sulphur dioxide and nitrogen dioxide. Air pollution is the contamination of air by impurities which may have a harmful impact on the living organisms and the non-living components. Sources of Air Pollution: Natural Sources: Smoke and dust arising from forest fires or volcanic eruptions. Methane gas arising from decaying organic matter. Man-made Sources: Exhaust gases from factories, power plants and automobiles. Carbon monoxide, nitrogen oxides, carbon dioxide, methane and sulphur dioxide are the major pollutants of air. Smog is a mix in the air of smoke and chemicals with fog. The chemical components of smog can include ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide. Smog can trigger breathing difficulties like asthma and coughing. Steps to prevent air pollution: • Use of fuels like CNG and unleaded petrol in automobiles. • Switching to alternative fuels, like solar energy, hydropower and wind energy. • Planting trees. • Travelling to school on a bicycle or on public transport or car pooling. • Avoiding the burning of leaves, trash and vegetable matter. • Restricting cigarette smoking. Increasing levels of greenhouse gases like CO2 ,CFC (Chloroflorocarbon) are leading to global warming. Excessive use of CFCs damages ozone layer which protects the earth from harmful UV rays emitted by the sun. Greenhouse Effect and Global Warming: The sun's rays warm the earth's surface. A part of the radiation that falls on the earth is absorbed by it and a part is reflected back into space. A part of the reflected radiation is trapped by the atmosphere due to presence of gases like water vapor, carbon dioxide, methane, nitrous oxide etc known as greenhouse gases. This is known as greenhouse effect. The trapped radiations further warm the earth and have adverse effects such as melting of glaciers and increasing sea levels. This phenomenon is known as global warming. Water pollution is the contamination of water by objectionable and harmful substances such as sewage, toxic chemicals, silt, etc. Sewage, agricultural chemicals and industrial waste are some of the major contaminants of water. Water which is purified and fit for drinking is known as potable water. Water is a precious natural resource. We must learn to conserve it.

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निम्नलिखित क्रियापदानां पदपरिचयं लिखत - (निम्नलिखित क्रिया पदों का पद परिचय लिखिए) पदम् धातु लकार पुरूष वचनम् 1. आसन - 2. निवसन्ति- 3. सन्ति- 4. भवेयु:- 5. आसीत् -

Posted by Netik Verma 1 year ago

CBSE > Class 08 > Sanskrit

1 answers

Saipriya Mishra 1 year ago

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Ashise deposite 50% of the initial amount in his locker. Sometime later he deposited 20% of the increase amount. Now the amount becomes 18000.how much was the initial amount

Posted by Rajni Devi 1 year ago

CBSE > Class 08 > Mathematics

1 answers

Swetleena Pati 1 year ago

14,400

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Find the square root of 610.0053361

Posted by Sulekha Kumari 1 year ago

CBSE > Class 08 > Mathematics

2 answers

Bhavya 😘 1 year ago

24.698

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D. Sadhana 1 year ago

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What is cumbtion

Posted by Swati Dawar 1 year ago

CBSE > Class 08 > Science

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Alok Gupta Ix 1 year ago

The burning of a substance is called cumbtion

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Satellits

Posted by Sejal Sherekar 1 year ago

CBSE > Class 08 > Computer

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Posted by Sejal Sherekar 1 year ago

CBSE > Class 08 > Computer

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Formulas of MS Excel

Posted by Probahan Dutta 1 year ago

CBSE > Class 08 > Computer

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Types of epimorphosis

Posted by Aditya Thakur 1 year ago

CBSE > Class 08 > Science

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Sonam Kumari 1 year ago

An example of epimorphosis invertebrates are: Regeneration of Limbs. Regeneration of Lenses. Regeneration of internal body organs.

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What is the difference between unpopular and controversial laws?

Posted by Pratyusha Singh 1 year, 1 month ago

CBSE > Class 08 > Social Science

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2. If a and b vary inversely to each other and a = 16 when b = 4 Find b when a = 8

Posted by Jayash Goel 1 year, 1 month ago

CBSE > Class 08 > Mathematics

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Posted by Sandhya Pandit 1 year ago

CBSE > Class 08 > English

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Q.No-1 You are going on a school picnic with your classmates and teachers. You are very excited. The night before the trip you sit down to write your diary. Describe what you have planned for the picnic and how you hope to enjoy yourself there. You are Ramesh. Write your dairy in 100-150 words. Q. No-2 You had the most difficult test today but you knew everything on the paper. You answered all the questions and you are really happy with how things turned out. Write a diary entry about it. Start with the anxiety you felt before you saw the question paper.

Posted by Saeeka Tarannum 1 year, 1 month ago

CBSE > Class 08 > English

1 answers

Khushi Shah 1 year ago

Dear dairy

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Tell what property allows one to compute 1/3*(6*4/3)as(1/3*6)*4/3

Posted by Darshan Nakum 1 year, 1 month ago

CBSE > Class 08 > Mathematics

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Translate English to Sanskrit on future tense

Posted by Ashmith Vp 1 year, 1 month ago

CBSE > Class 08 > Sanskrit

1 answers

Ankush Jha 1 year, 1 month ago

I don't know

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Factorise a) 12x²-9x

Posted by Anuj Sharma 1 year, 1 month ago

CBSE > Class 08 > Mathematics

1 answers

Bhavya 😘 1 year ago

3x(4x-3)

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What are the different types of farming? Explain

Posted by Siya Kurmi 1 year, 1 month ago

CBSE > Class 08 > Social Science

2 answers

Sandeep Mahala 1 year ago

CBSE notes

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Rohit Ks 1 year ago

There

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Give mindmap for Geography lesson Agriculture

Posted by Haricharan A 1 year, 1 month ago

CBSE > Class 08 > Social Science

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Mallikarjun Rajoli 1 year ago

What is agriculture

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Bravia book 9.6 exercise

Posted by Tejas Balda 1 year, 1 month ago

CBSE > Class 08 > English

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You friend behaved very selfishly in the canteen today and you are so upset share you experient using diary entry

Posted by M Rakeshwar Reddy Reddy. 1 year, 1 month ago

CBSE > Class 08 > English

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Name any activities to safeguard the computer from trojan

Posted by Brar Kaur 1 year, 1 month ago

CBSE > Class 08 > Computer

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Mind map for agriculture lesson

Posted by Sujay S 1 year, 1 month ago

CBSE > Class 08 > Social Science

2 answers

Sobhita Maharana 1 year, 1 month ago

What is the difference between Mahalwari system and Ryotwari system?

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Hargun Sandhu Harmit 1 year, 1 month ago

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Paad 6

Posted by Dg Dg 1 year, 1 month ago

CBSE > Class 08 > Sanskrit

2 answers

Rudransh Karande 11 months, 2 weeks ago

Auukat

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Pratyaksh Jaiswal 1 year ago

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Compare the condition of public facility of Chennai with your city (Bangalore)

Posted by Chandan Chintu 1 year, 1 month ago

CBSE > Class 08 > Social Science

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Factorise the expression and divide them as directed 39y^3 (50y^2 -98)÷ 26y^2 (5y+7)

Posted by Bhavishya Patel 1 year, 1 month ago

CBSE > Class 08 > Mathematics

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Assertion ya reasoning ka matlab kya

Posted by Sampreethi Sampreethi 1 year, 1 month ago

CBSE > Class 08 > Reasoning & Mental Ability

2 answers

Soumya Waingade 8 months, 4 weeks ago

Assertion is a given statement.. Reason is assertion ka appropriate reason

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Prabal Kumar 10 months, 3 weeks ago

Assertion means : a confident and forceful statement of fact or belief. Reasoning means : the action of thinking about something in a logical, sensible way.

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Davath ka mathlab kya

Posted by Sampreethi Sampreethi 1 year, 1 month ago

CBSE > Class 08 > हिंदी