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1. Atoms and Molecules B-1-B-14

2. Structure of Atom B-15-B-26

3. Diversity in living Organisms B-37-B-38

4. Properties of fluids B-39-B-50

5. Work and Energy B-51-B-62

6. Sound B-63-B-80

7. Why Do We Fall Ill B-81-B-92

8. Natural Resources B-93-B-102

IndexPART A : OTBA ANALYSIS, QUESTIONS & ANSWERS

SUBJECT 1 - SCIENCE

1. Clean Air - A Shared Concern A-1-A-18

2. Environment and Development - Lessons from the Hills A-19-A-36

SUBJECT 2 - ENGLISH

1. Information Technology and Values A-37-A-55

2. The Future is Now: A Zest for Living A-56-A-72

SUBJECT 3 - HINDI

1. cky etnwjh A-73-A-85

2. ckyd & ckfydkvksa dk vleku fyax vuqikr A-86-A-98

PART B : CHAPTER-WISE QUICK REVISION NOTES,

NCERT SOLUTIONS AND PRACTICE QUESTION BANK

PART C : SAMPLE PAPERS WITH SOLUTIONS FOR SA2

• SAMPLE PAPER-1 C-1-C-12

• SAMPLE PAPER-2 C-13-C-22

• SAMPLE PAPER-3 C-23-C-32

PART AOTBA ANALYSIS,

QUESTIONS & ANSWERSA-1-A-98

Abstract:

Human activities have put water and air in a bad state

Let’s save, freshen and conserve them before it is too late.

Clean air is vital for the existence and continuance of all living organisms on earth. Naturallyexisting mixture of gases in the atmosphere, comprising of mainly Nitrogen, Oxygen, Carbondioxide and water vapours, provides excellent conditions to support and sustain life. However,this natural composition of air is getting disturbed due to variety of human activities. Humanactivities related to mainly industry, vehicular emissions, burning of fossil fuels, accidentalnuclear emissions etc. contaminate the natural air with undesired components resulting in airpollution. These components, called pollutants, are not only harmful for living organisms butalso affect non–living things adversely. The situation is quite alarming, particularly in bigindustrialized cities. With worldwide trend of shifting of human population to cities and theirhuman desire to lead more comfortable life, the issues and concerns related to availability ofclean air for survival are becoming a great challenge for everyone.

The present text attempts to help the reader comprehend the situation in a holistic manner, identifythe causes and effects of air pollution, examine and analyze the existing status, reflect, debate andgenerate ideas as to what actions need to be taken at individual, collective or governmental level tomeet the emerging challenges.

The Context

The atmosphere surrounding the earth is a mixture of many gases which, along with the other conditions,makes it a unique planet for existence of life. Unprecedented urbanisation and development duringthe past few centuries and many human activities have disturbed the natural composition of thisatmosphere. It is unfortunate that the cost of development is very heavy and is being paid by causinga severe damage to the life support system in the form of clean air.

The contamination of air with undesirable gases and particulate matter is called air pollution. Thesubstances which cause pollution are called pollutants. These are either gaseous pollutants like oxidesof carbon, sulphur, nitrogen etc. or particulate matter in the form of dust, smoke, fumes or mist. Aperson living in a city with polluted air is likely to suffer from one or the other breathing problem.

SCIENCE

Clean Air - A SharedConcern1

A-2 SCIENCE & TECHNOLOGY

Picture: 1Source: http://www.cartoonstock.com,

http://oneair.webs.com

Picture: 2Source: http://oneair.webs.com

To sensitize people towards keeping the planet Earth non polluted, Earth Day, an annual event, iscelebrated on April 22. On this day, programmes are held worldwide to sensitize people towardsenvironmental protection. People are made aware that if they do not act collectively, the green cleanenvironment will be only for the pictures.

Picture : 3Picture : 3

Source : htt//www.tumblr.net

Carbon dioxide is necessary for the survival of life on Earth as it is an essential raw material for theprocess of photosynthesis and green house effect. This effect is essential to maintain and keep the

Case & Analysis A-3

earth’s atmosphere warm to sustain life. But due to excessive burning of fossil fuels and other carboncontaining fuels, there has been an excessive release of CO2 in the atmosphere. The increasing CO2levels in the atmosphere lead to excessive heating of the earth’s surface. The heating results into anew phenomenon called Global Warming. Besides carbon dioxide, the other green house gasespresent in the earth’s atmosphere in their order of abundance are; water vapour, carbon dioxide,methane, nitrous oxide, ozone and chlorofluorocarbons.

The gaseous and particulate pollutants together cause further damage to life. Have you ever observedthat visibility is very low during winters due to fog? Smog is a mixture of smoke dust particles and fog.This phenomenon increases during heavy traffic hours in cities. The reason is that smoke emittedfrom the exhaust of the vehicles settles over fog in winter and reduces the visibility.

We all know about the smoke laden fog, called smog, which surrounded the city of London in the year1952. It resulted in the loss of about 4000 human lives and many others suffering from seriousbreathing problems according to the available press reports. Even the cattle had been asphyxiated bythe smog. The unfortunate accident gave a rude shock to the Governments of different nations andthe problem of air pollution took a central stage.

The human lifestyle in many developed countries is also causing another serious problem in the formof depletion of ozone layer. The use of refrigerators and air conditioners, fire extinguishers, aerosolsprays like deodorants etc. results in release of CFCs and N2O in the atmosphere which is responsiblefor depletion of ozone layer. This results in ultraviolet radiations entering the atmosphere unobstructedcausing damage to all kinds of life on Earth.

Picture: 4Source: www.pnuma.org

Many organizations are coming forward to create awareness among the masses so that we leave acleaner planet for the coming generations.

continue

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