Category: CBSE Class 9

On this page, you will find NCERT Class 9 Civics Chapter 4 Notes Pdf free download. CBSE Class 9 Social Science Notes Civics Chapter 4 SST Electoral Politics will seemingly, help them to revise the important concepts in less time.

Electoral Politics Class 9 Notes Social Science Civics Chapter 4

CBSE Class 9 Civics Chapter 4 Notes Understanding the Lesson

1. The most common form of democracy in our times is for the people to govern through their representatives. These representatives are elected bodies.

2. Elections are necessary and useful in a democracy. All democratic countries hold elections.

3. Elections are all about political competition. This competition takes various forms. The most obvious form is the competition among political parties.

4. Although an electoral competition has many demerits, our Constitution makers opted for free competition in elections as the way to select our future leaders. The did so because this system works better in the long run.

5. Regular electoral competition provides incentives to political parties and leaders. They know that if they raise issues that people want to be raised, their popularity and chances of victory will increase in the next elections.

6. If a political party is motivated only by desire to be in power, even then it will be forced to serve the people.

7. In India, Lok Sabha and Vidhan Sabha elections are held regularly after every five years. After five years the term of all the elected representatives comes to an end.

8. Elections are held in all constituencies at the same time, either on the same day or within a few days. This is called a general election. Sometimes by-elections are held to fill the vacancy caused by death or resignation of a member.

9. Our country is divided into different areas for purposes of elections. These areas are called electoral constituencies. The voters who live in an area elect one representative.

10. For Lok Sabha elections, the country is divided into 543 constituencies. The representative elected from each constituency is called a Member of Parliament or an MP.

11. Similarly, each state is divided into a specific number of Assembly Constituencies. In this case, the elected representative is called the Member of Legislative Assembly or a MLA.

12. In Panchayat and Municipal Elections, each village or town is divided into several wards. Each ward elects one member of the village or the urban local body.

13. Some constituencies are reserved for people who belong to the Scheduled Castes (SC) and Scheduled Tribes (ST). This system of reservation was extended later to other weaker sections at the district and local level.

14. In a democratic election, the list of those who are eligible to vote is prepared much before the election and given to everyone. This list is called the Voters’ List.

15. In our country, all the citizens aged 18 years and above can vote in an election. Every citizen has the right to vote, regardless of his /her caste, religion or gender.

16. Political parties nominate their candidates who get the party symbol and support. Party’s nomination is often called party ‘ticket’.

17. Every person who wishes to contest an election has to fill a nomination form and give some money as security deposit. Recently, a new system of declaration has been introduced on direction from the Supreme Court. Every candidate has to make a legal declaration, giving details of his/her assets and liabilities, educational qualification, etc.

18. In our country election campaigns take place for a two week period between the announcement of the final list of candidates and the date of polling.

19. During election campaigns, the candidates contact their voters, political leaders, address election meetings and political parties mobilize their supporters.

20. The final stage of an election is the day when the voters cast their vote. That day is usually called the election day. Nowadays electronic voting machines EVMs are used to record votes.

21. Once the polling is over, all the EVMs are sealed and taken to a secure place. A few days later, on a fixed day, all the EVMs from a constituency are opened and the votes secured by each candidate are counted.

22. The candidate who secures the highest number of votes from a constituency is declared elected. In a general election, counting of votes in all constituencies takes place at the same time, on the same day. Within a few hours of counting, all the results are declared and it becomes clear as to who will form the next government.

23. In our country elections are conducted by an independent and very powerful Election Commission or EC. It enjoys wide-ranging powers. It takes decisions on every aspect of conduct and control of elections from the announcement of elections to the declaration of results. It can reprimand the j government and administration for their lapses.

24. People’s participation in election is usually measured by voter turnout figures. Turnout indicates the percent of eligible voters who actually cast their vote.

25. In India the poor, illiterate and underprivileged people vote in larger proportion as compared to the rich and privileged sections. This is in contrast to western democracies.

26. The final test of the free and fair election is its outcome. The electoral outcomes are usually accepted as people’s verdict by the defeated party.

27. There are many limitations and challenges of Indian elections. Some of them are-candidates and parties with a lot of money may not be sure of their victory but they do enjoy a big and unfair advantage over smaller parties, some families tend to dominate political parties, etc.

28. Citizens, social activists and organizations have been demanding reforms in our electoral system.

Electoral Politics Class 9 CBSE Notes Important Terms

Constituency: Voters in a geographical area who elect a representative to the legislative bodies.

Code of conduct: A set of norms and guidelines to be followed by political parties and contesting candidates during election time.

Rigging: Fraud and malpractices indulged by a party or candidate to increase its voters.

Booth capturing: Supporters or hired musclemen of party or a candidate gain physical control of a polling booth and cast false votes by threatening everyone or preventing genuine voters from reaching the polling booth.

Turnout: The percentages of eligible voters who cast their votes in an election.

Incumbent: The current holder of a political office.

Level playing field: Condition in which all parties and candidates contesting in an election have equal opportunities to appeal for votes and to carry out election campaign.

On this page, you will find NCERT Class 9 Civics Chapter 3 Notes Pdf free download. CBSE Class 9 Social Science Notes Civics Chapter 3 SST Constitutional Design will seemingly, help them to revise the important concepts in less time.

Constitutional Design Class 9 Notes Social Science Civics Chapter 3

CBSE Class 9 Civics Chapter 3 Notes Understanding the Lesson

1. In a democracy the rulers are not free to do what they like. There are certain basic rules that the citizens and the government have to follow. All such rules together are called Constitution.

2. Constitution is the supreme law that determines the relationship among people living in a territory and also the relationship between the people and government.

3. All countries that have constitutions are not necessarily democratic. But all countries that are democratic will have constitutions.

4. South Africa attained independence from the apartheid government in 1994 and Nelson Mandela became the first president of the country.

5. A big task was ahead before the party that ruled through oppression and the party that led the freedom struggle to sit together to draw up a common Constitution.

6. After two years of discussion and debate they came out with one of the finest constitutions the world has ever had. This Constitution gave to its citizens the most extensive rights available in any country.

7. The South African Constitution inspires democrats all over the world. The people of the country played an important role in it. They along with the leaders worked together and finally transformed better experiences into the binding glue of a diverse nation.

8. Like South Africa, India’s Constitution was also drawn up under very difficult circumstances. The making of the Constitution for a huge and diverse country like India was not an easy affair. The makers of the Constitution had anxieties about the present and the future of the country.

9. Prominent leaders like Rajendra Prasad and Dr B. R. Ambedkar played an important role in the making of the Constitution. They were inspired by the ideals of French Revolution, the practice of parliamentary democracy in Britain and the Bill of Rights in the US. The socialist revolution in Russia had also its impact on the leaders.

10. The drafting of the document called the Constitution was done by the Constituent Assembly. It had 299 members who wrote the Constitution. The Assembly adopted the Constitution on 26 November, 1949 but it came into effect on 26 January 1950.

11. The Constituent Assembly worked in a systematic, open and consensual manner. First some basic principles were decided and agreed upon. Then a draft of Constitution was prepared for discussion.

12. The Preamble of the Constitution reads like a poem on democracy. It contains the philosophy on which the entire Constitution has been built. It is the soul of the Indian Constitution.

13. Some of the key words used in the Preamble of our Constitution are-sovereign, socialist, secular, democratic, republic, justice, liberty, equality and fraternity.

14. The Constitution of India is a very long and detailed document. Therefore, it needs to be amended quite regularly to keep it updated. The Constitution makers made provisions to incorporate changes from time to time. These changes are called constitutional amendments.

15. The Constitution describes the institutional arrangements in a very legal language. Like any Constitution, the Indian Constitution lays down a procedure for choosing persons to govern the country.

16. It decides who will have how much power to take which decisions. And it puts limits to what the government can do by providing some rights to a citizen that cannot be violated.

Constitutional Design Class 9 CBSE Notes Important Terms

Apartheid: The official policy of racial separation and ill-treatment of blacks followed by the government of South Africa between 1948 and 1989.

Domination: The exercise of power or influence over someone or something, or the state of being so controlled.

Treason: The crime of betraying one’s country, especially by attempting to kill or overthrow the sovereign or government.

Racial discrimination: When a person is treated less favourably than another person in a similar situation because of his/her race, colour, ethnic origin, etc.

Segregation: The action or state of setting someone or something apart from others.

Constitution: Supreme law of a country, containing fundamental rules governing the politics and society in a country.

Preamble: An introductory statement in a Constitution which states the reasons and guiding values of the Constitution.

Citizens: People living in a territory.

Diverse: Showing a great deal of variety.

Universal Adult Franchise: It means all citizens whose age is above 18 have the right to vote.

Constituent Assembly: An assembly of people’s representatives that writes a Constitution for country.

Draft: A preliminary version of a legal document.

Clause: A distinct section of a document.

Philosophy: The most fundamental principles underlying one’s thoughts and actions.

Untouchability: A status of certain social groups (Dalits) confined to menial and despised jobs.

Tryst: A meeting or meeting place that has been agreed upon.

Secular: Not connected with religions or spiritual matters.

Democratic: A form of government where people enjoy equal political rights, elect their rulers and held them accountable.

Republic: A state which has an elected or nominated President rather than a monarch.

Liberty: Absence of unreasonable restrictions on the citizens in what they think, how they wish to express their thoughts, etc.

Fraternity: Friendship and mutual support within a group.

On this page, you will find NCERT Class 9 Civics Chapter 2 Notes Pdf free download. CBSE Class 9 Social Science Notes Civics Chapter 2 SST What is Democracy? Why Democracy? will seemingly, help them to revise the important concepts in less time.

What is Democracy? Why Democracy? Class 9 Notes Social Science Civics Chapter 2

CBSE Class 9 Civics Chapter 2 Notes Understanding the Lesson

1. Democracy is a form of government in which the rulers are elected by the people. It is the most prevalent form of government in the world today and it is expanding to more countries. It is better than other forms of government.

2. In a democracy, major decisions are taken by those elected by the people. A democracy must be based on a free and fair election where those currently in power have a fair chance of losing.

3. Democracy is based on a fundamental principle of political equality. It means that in a democracy, each adult citizen must have one vote and each vote must have one value.

4. A democratic government cannot do whatever it likes, simply because it has won an election. It has to respect some basic rules. In particular it has to respect some guarantees to the minorities.

5. Democracy is better than other forms of government because it is a more accountable form of government. It improves the quality of decision-making and enhances the dignity of citizens. Democracy also allows us to correct its own mistakes.

6. arguments are given against democracy-leaders keep changing in democracy which leads to instability, democracy is all about political competition and power play, democracy leads to corruption for it is based on electoral competition, etc.

7. Democracy cannot get us everything and it is not the solution to all problems. But it is clearly better than any other alternatives that we know. It offers better chances of a good decision.

8. The most common form that democracy takes in our times is that of representative democracy. In the countries we call democracy, all the people do not rule. A majority is allowed to take decisions on behalf of all the people. Even the majority does not rule directly. The majority of people rule through their elected representatives.

9. It is also important to distinguish between a democracy and a good democracy. A good democracy is dedicated for the cause of the poor and the helpless. A good democracy is that which provides every citizen equal right to vote, equal information, basic education and equal resources.

10. No country is a perfect democracy. However, every democracy has to try to realise the ideals of a democratic decision-making. This cannot be achieved once and for all. This requires a constant effort to save and strengthen democratic forms of decision-making.

11. We as citizens can also play important role in making our country more or less democratic. Other forms of government do not require all citizens to take part in politics. But democracy depends on active political participation by all the citizens.

What is Democracy? Why Democracy? Class 9 CBSE Notes Important Terms

Democracy: A form of government in which rulers are elected by the people.

Contemporary: Living or occurring at the same time.

Election: A formal decision-making process by which a population chooses an individual to hold public office.

Designation: A official name, description, or title.

Malpractices: Injurious, negligent, or improper practices.

Campaign: An organised effort which seeks to influence the decision-making process within a specific group.

Autocratic: Relating to a ruler who has absolute power.

Accountable: Required or expected to justify actions or decisions; responsible.

Minority: The smaller number or part, especially a number or part representing less than half of the whole.

On this page, you will find NCERT Class 9 Geography Chapter 6 Notes Pdf free download. CBSE Class 9 Social Science Notes Geography Chapter 6 SST Population will seemingly, help them to revise the important concepts in less time.

Population Class 9 Notes Social Science Geography Chapter 6

CBSE Class 9 Geography Chapter 6 Notes Understanding the Lesson

1. Population is an important topic in social studies. Everything such as resources, calamities, disasters, etc. are meaningful only in relation to human beings.

2. Human beings are producers and consumers of earth’s resources. Therefore, it is important to know how many people are there in a country, where do they live, how and why their numbers are increasing and what are their characteristics. The Census of India provides us with information regarding the population of our country.

3. India’s population as on March 2011 stood at 1,210 million, which account for 17.5 per cent of the world’s population. These 1.21 million people are unevenly distributed.

4. The 2011 Census data reveals that Uttar Pradesh with a population size of 199 million people is the most populous state of India. On the other hand, Sikkim has a population of just about 0.6 million and Lakshadweep has only 64,429 thousand people.

5. Almost half of India’s population lives in just five states-Uttar Pradesh, Maharashtra, Bihar, West Bengal and Andhra Pradesh.

6. The population density of India in the year 2011 was 382 persons per sq. km. Densities vary from 1,102 persons per sq. km in Bihar to only 17 persons per sq. km in Arunachal Pradesh.

7. The numbers, distribution and composition of the population are constantly changing due to births, deaths and migrations.

8. Growth of population can be expressed in two ways-in terms of absolute numbers and in terms of percentage change per year.

9. India’s population has been steadily increasing from 361 million in 1951 to 1210 million in 2011. From 1951 to 1981, the annual rate of population growth was steadily increasing. Since 1981, however the rate of growth started declining gradually.

10. The declining trend of the growth rate is indeed a positive indicator of the efforts of birth control.

11. There are three main processes of change of population-birth rates, death rates and migration. The natural increases of population is the difference between birth rates and death rates.

12. In India, most migrations have been from rural to urban areas which provide increased employment opportunities and better living conditions.

13. The urban population has increased from 17.29 per cent of the total population in 1951 to 31.80 per cent in 2011. There has been a significant increase in the number of million-plus cities from 35 to 53 in just one decade, i.e. 2001 to 2011.

14. Age composition is one of the most basic characteristics of a population.

15. The population of a nation is generally grouped into three broad categories—Children below 15 years, Working age (15-59 years) and Aged (above 59 years).

16. Sex ratio is an important social indicator to measure the extent of equality between males and females in a society at a given time. The sex ratio in the country has always remained unfavourable to females.

17. Literacy is an important quality of a population. Low levels of literacy are a serious obstacle for economic improvement.

18. The percentage of population that is economically active is an important index of development.

19. A great number of occupations are found in any country. These occupations are generally classified as primary, secondary and tertiary.

20. The percentage of people working in different activities varies in developed and developing countries. Developed nations have a high proportion of people in secondary, and tertiary activities. Developing countries tend to have a higher proportion of their workforce engaged in primary activities.

21. Health is an important component of population composition. Sustained efforts of government programmes have made significant improvements in the heath conditions of the Indian population.

22. Despite considerable achievements, the health situation is a matter of major concern for India. The per capita calorie consumption is much below the recommended levels and malnutrition afflicts a large percentage of our population.

23. Adolescent population constitutes one-fifth of the total population of India. Adolescents are generally grouped in the age-grouped of 10 to 19 years. They are the most important resource for the future.

24. The diet available to adolescents is inadequate in all nutrients. A large number of adolescent girls suffer from anaemia.

25. The National Population Policy (NPP) provides a policy framework for imparting free and compulsory school education up to 14 years of age, reducing infant mortality rate to below 30 per 1000 live births, achieving universal immunisation of children against all vaccine-preventable diseases, etc.

26. Education and heath should be given much importance because a well-educated healthy population can play an important role in country’s development.

Population Class 9 CBSE Notes Important Terms

Adolescence: A period in which a person is no longer a child and not yet an adult. Such persons are grouped in the age-group of 10 to 19 years.

Birth rate: The number of live births for every 100 persons in a year.

Census: An official enumeration of population done periodically.

Population density: The number of persons per unit area.

Population growth: Change in the number of inhabitants of a country/territory during a specific period of time.

Death rate: The number of deaths per thousand persons in a year.

Migration: The movement of people across regions and territories.

Sex ratio: The number of females per thousand males.

Literacy: The ability to read, write and use arithmetic.

On this page, you will find NCERT Class 9 Geography Chapter 5 Notes Pdf free download. CBSE Class 9 Social Science Notes Geography Chapter 5 SST Natural Vegetation and Wildlife will seemingly, help them to revise the important concepts in less time.

Natural Vegetation and Wildlife Class 9 Notes Social Science Geography Chapter 5

CBSE Class 9 Geography Chapter 5 Notes Understanding the Lesson

1. India has a wonderful plant diversity. It is blessed with about 47,000 plant species. There are about 15,000 flowering plants in our country which account for 6 per cent in the world’s total number of flowering plants.

2. India also has approximately 90,000 species of animals as well as a rich variety of fish in its marine waters.

3. Natural vegetation grows naturally without human aid. Cultivated crops and fruits, orchards form part of vegetation but not natural vegetation.

4. The huge diversity in flora and fauna kingdom is due to the factors, such as—relief (land and soil), climate (temperature, sunlight and precipitation) and ecosystem.

5. All the plants and animals in an area are interdependent and inter-related to each other in their physical environment.

6. Human beings are also integral part of the ecosystem. They utilise vegetation and wildlife. But their greed leads to over-utilisation of these resources.

7. There are five types of vegetation-tropical evergreen, tropical deciduous, tropical thorn forests and scrubs, montane and mangrove forests.

8. Tropical evergreen forests are found in the heavy rainfall areas. They are at their best in areas having more than 200 cm of rainfall with a short dry season. The trees reach great heights up to 60 metres or even above. Trees like ebony, mahogany, rosewood, rubber and cinchona and animals like elephants, monkeys, lemur and deer are found in these forests.

9. Tropical deciduous forests are also called the monsoon forests and spread over the region receiving rainfall between 200 cm and 70 cm. On the basis of the availability of water, these forests are divided into moist and dry deciduous. Trees like teak, sal, peepal and neem and animals such as lion, pig, deer and elephants are found in these forests.

10. The thorn forests and scrubs are found in regions with less than 70 cm of rainfall. Acacias, palms, euphorbias and cacti are the main plant species. Animals such as rats, mice, rabbits tigers, etc. are found in these forests.

11. Montane forests are found in mountainous areas. Trees like oaks and chestnuts are found between a height of 1000 and 2000 metres. Between 1500 and 3000 metres, temperate forests containing coniferous trees like pine, deodar, silver fir, etc. are found. The common animals found in these forests are Kashmir stag, spotted deer, wild sheep, jackrabbit, Tibetan antelope, etc.

12. The mangrove tidal forests are found in the areas of coasts influenced by tides. Trees such as Sundari, palm, coconut, keora, etc. are found in these forests. Royal Bengal Tiger is the famous animal in these forests.

13. Wildlife: India is equally rich in its fauna. It has approximately 90,000 of animal species. Its shares between 5 and 8 per cent of the world’s amphibians, reptiles and mammals.

14. The elephants are found in the hot wet forests of Assam, Karnataka and Kerala. One-horn rhinoceroses live in swampy and marshy lands of Assam and West Bengal.

15. India is the only country in the world that has both tigers and lions. The natural habitat of the Indian lion in the Gir forest in Gujarat. Ladakh’s freezing high altitudes are home to yak, the shaggy homed wild ox, etc.

16. In the rivers, lakes and coastal areas, turtles, crocodiles and gharials are found. Birdlife in India is colourful. Peacocks, pheasants, ducks, parakeets, cranes and pigeons are found in the forests and wetlands of the country.

17. Due to excessive exploitation of the plants and animal resources by human beings, the ecosystem has been disturbed. About 1,300 plant species are endangered and 20 species are extinct.

18. Fourteen biosphere reserves have been set up in the country to protect flora and fauna. Project Tiger, Project Rhino, Project Great Indian Bustard and many other eco-developmental projects have been introduced by the government. National Parks, Wildlife sanctuaries and zoological gardens have been set up to protect natural heritage.

Natural Vegetation and Wildlife Class 9 CBSE Notes Important Terms

Vegetation: Plants considered collectively, especially those found in a particular area or habitat.

Flora: Plants a particular region or period.

Fauna: Species of animals.

Brome: A very large ecosystem on land having distinct types of vegetation and animal life.

Wildlife: Wild animals collectively, the native fauna and sometimes flora of a region.

Ecosystem: A biological community of interacting organisms and their physical environment.

On this page, you will find NCERT Class 9 Geography Chapter 4 Notes Pdf free download. CBSE Class 9 Social Science Notes Geography Chapter 4 SST Climate will seemingly, help them to revise the important concepts in less time.

Climate Class 9 Notes Social Science Geography Chapter 4

CBSE Class 9 Geography Chapter 4 Notes Understanding the Lesson

1. Climate refers to the sum total of weather conditions and variations over a large area for a long period of time.

2. Weather refers to the state of the atmosphere over an area at any point of time.

3. The elements of weather and climate are the same i.e., temperature, atmospheric pressure, wind, humidity and precipitation.

4. The climate of India is described as the monsoon type. Temperature and precipitation vary from place to place and season to season.

5. In upper parts of Himalayas precipitation is mostly in the form of snowfall but in the rest of the country it rains. Most parts of the country receives rainfall from June to September. There is decrease in rainfall generally from east to west in the Northern Plains.

6. There are six major controls of the climate of any place-latitude, altitude, pressure and wind system, distance from the sea, ocean currents and relief features.

7. India’s climate has characteristics of tropical as well as sub-tropical climates. The Himalayas in the north of India prevent the cold winds from Central Asia from entering the sub-continent.

8. The climate and associated weather conditions in India are governed by-pressure and surface winds, upper air circulation; and western cyclonic disturbances and tropical cyclones.

9. The pressure and wind conditions over India are unique. During winter, there is a high-pressure area north of the Himalayas. In summer, a low-pressure area develops over interior Asia as well as over northwestern India.

10. The climate of India is strongly influenced by monsoon winds. The monsoons are experienced in the tropical area roughly between 20°N and 20°S.

11. The duration of monsoon in India is between 100-120 days from early June to mid-September. It arrives at the southern tip of the Indian peninsula by the first week of June. Subsequently, it proceeds into two-the Arabian sea branch and the Bay of Bengal branch.

12. The Arabian sea branch reaches Mumbai by the 10^th of June and the Bay of Bengal branch arrives in Assam in the first week of June. Both these branches merge over the northwestern part of the Ganga plains.

13. The retreat of the monsoon begins in northwestern states of India by early September. By mid- October, it withdraws completely from the northern half of the peninsula. By early December, the monsoon has withdrawn from the rest of the country.

14. Four seasons can be identified in India-the cold-weather season, the hot weather season, the advancing monsoon and the retreating monsoon with some regional variations.

15. The cold-weather season begins from mid-November in northern India and stays till February. The hot-weather season remains from March to May. The rainy season starts from early June. By the beginning of October, the monsoon withdraws from the Northern plains.

16. December and January are the coldest in the northern part of India. The summer months experience rising temperature and falling air pressure in this part.

17. ‘Loo’ is a striking feature of the hot weather season. It blows over the north and northwestern India.

18. The retreat of monsoon is marked by clear skies and rise in temperature. While day temperature are high, nights are cool and pleasant.

19. Distribution of rainfall varies from place to place. It is highest in parts of western coast and northeastern India and lowest in western Rajasthan and adjoining parts of Gujarat, Haryana and Punjab.

20. Areas of high rainfall are liable to be affected by floods and areas of low rainfall are drought-prone.

21. The uncertainties of rain and uneven distribution are very much typical of the monsoons. The Indian landscape, its animal and plant life, its entire agriculture calender and the life of the people, revolve around this phenomenon.

Climate Class 9 CBSE Notes Important Terms

Weather: The state of atmosphere over an area of at any point of time.

Climate: The sum total of weather conditions and variation over a large area for a long period of time.

Monsoon: The seasonal prevailing wind in the region of South and South East Asia, blowing from the south-west between May and September and bringing rain.

Precipitation: Rain, snow, sleet or hail that falls to or condenses on the ground.

Loo: Strong, gusty, hot, dry winds blowing during the day over the north and north-western India.

Mahawat: The local name for the total amount of winter rainfall.

Relief: The highest and lowest elevation points in an area.

On this page, you will find NCERT Class 9 Geography Chapter 3 Notes Pdf free download. CBSE Class 9 Social Science Notes Geography Chapter 3 SST Drainage will seemingly, help them to revise the important concepts in less time.

Drainage Class 9 Notes Social Science Geography Chapter 3

CBSE Class 9 Geography Chapter 3 Notes Understanding the Lesson

1. The term ‘Drainage’ describes the river system of an area. The area drained by a single river system is called a drainage basin.

2. Any mountain or an upland separating two drainage basins is called a water divide.

3. The Indian rivers are divided into two major groups

• the Himalayan rivers and
• The peninsular rivers.

4. Some of the features of the Himalayan rivers are-they are perennial, they have long courses from heir source to the sea, they perform intensive erosional activity in their upper courses and carry huge loads of silt and sand.

5. Some of the features of the Peninsular rivers are-they are seasonal, they have shorter and shallower courses as compared to the Himalayan rivers, most of them originate in the Western Ghats and flow towards the Bay of Bengal.

6. The streams within a drainage basin form certain patterns, depending on the slope of land, underlying rock structure as well as the climatic conditions of the area.

7. Types of drainage patterns are-dendrite, trellis, rectangular and radial patterns.

8. The major Himalayan rivers are-the Indus, the Ganga and the Brahmaputra. The river Indus rises in Tibet, near Lake Mansarovar. It flows through Baltistan and Gilgit and emerges from the mountains at Attock. The Indus plain has a very gentle slope. The Indus is one of the longest rivers of the world.

9. The Ganga emerges from the mountains on to the plains at Haridwar. The river is joined by tributaries such as the Yamuna, the Ghaghara, the Gandak and the Kosi. The length of the Ganga is over 2500 km.

10. The Brahmaputra is slightly longer than the Indus and most of its course lies outside India. The river rises in Tibet east of Mansarovar lake. It flows eastwards parallel to the Himalayas. Every year during the rainy season, the river overflows its banks, causing widespread devastation due to floods in Assam and Bangladesh.

11. Major rivers of the Peninsula such as the Mahanadi, the Godavari, the Krishna and the Kaveri flow eastwards and drain into the Bay of Bengal. These rivers make deltas at their mouths. The Narmada and the Tapi flow west and make estuaries.

12. The Narmada rises in the Amarkantak hills in the Madhya Pradesh. On its way to the sea, it creates many picturesque sites. The Narmada basin covers parts of Madhya Pradesh and Gujarat.

13. The Tapi rises in the Satpura ranges, in the Betul district of Madhya Pradesh. Its basin covers parts of Madhya Pradesh, Gujarat and Maharashtra.

14. The Godavari, the largest Peninsular river, rises in the Nasik district of Maharashtra. Its basin covers parts of Maharashtra, Madhya Pradesh, Odisha and Andhra Pradesh.

15. The Mahanadi rises in the highlands of Chhattisgarh. Its drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand and Odisha.

16. The Krishna rises from a spring near Mahabaleshwar. It drains into the Bay of Bengal. Its drainage basin is shared by Maharashtra, Karnataka and Andhra Pradesh.

17. The Kaveri rises in the Brahmagri range of the Western Ghats and it reaches the Bay of Bengal in south of Cuddalore, in Tamil Nadu. Its basin drains parts of Karnataka, Kerala and Tamil Nadu.

18. India has many lakes which differ from each other in size, and other characteristics. Most lakes are permanent while some contain water only during the rainy season.

19. Some of the lakes have come into existence as the result of the action of glaciers and ice sheets while the others have been formed by wind, river action and human activities.

20. Most of the fresh-water lakes are in the Himalayan region. The Wular lake in Jammu and Kashmir is the largest freshwater lake in India. Some lakes such as Guru Gobind Sagar have been artificially created by damming of rivers for power generation.

21. Rivers play an important role in country’s economy. Their water is used for irrigation, navigation, hydro-power generation, etc.

22. Excess use of river water has affected its quality. Untreated sewage and industrial effluents are emptied into the rivers as a result of which their self-cleansing capacity is lost.

23. Increasing urbanization and industrialization are also major reasons of river pollution. It is high time to think over it and do accordingly.

Drainage Class 9 CBSE Notes Important Terms

Drainage: The river system of an area.

Drainage basin: The area drained by a single river system.

Water divide: Any mountain or an upland that separates two drainage basins is called a water divide.

Perennial rivers: Rivers having water throughout the year.

River system: A river along with its tributaries.

Seasonal rivers: Rivers having water only during rainy season.

Floodplain: An area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.

River delta: A landform that forms from deposition of sediment carried by a river as the flow leaves its mouth and enters slower-moving or standing water.

Gorges: Deep, narrow valleys with a stream or river running along their bottom.

Bhagirathi: The headwaters of the Ganga.

Tributary: A river or stream flowing into a larger river or lake.

Glacier: A slowly moving mass or river of ice formed by the accumulation and compaction of snow on mountains or near the poles.

Distributary: A branch of a river that does not return to the mainstream after leaving it as in a delta.

Meander: A winding curve or bend in a river.

Rift valley: A linear-shaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault.

Lake: A large area of water surrounded by land.

Sea: A lake of large extent.

Trough: A narrow depression as in the earth or between ocean waves or in the ocean bed. A narrow channel, gutter or gulley.

On this page, you will find NCERT Class 9 Geography Chapter 1 Notes Pdf free download. CBSE Class 9 Social Science Notes Geography Chapter 1 SST India Size and Location will seemingly, help them to revise the important concepts in less time. India Size and Location

India Size and Location Class 9 Notes Social Science Geography Chapter 1

CBSE Class 9 Geography Chapter 1 Notes Understanding the Lesson

1. India lies entirely in the Northern Hemisphere. The mainland extends between latitudes 8°4′ N and 37°6′ N and longitudes 68°7′ E and 97°25′ E. The Tropic of Cancer divides the country in two halves. The landmass of India has an area of 3.28 million square km. India’s total area accounts for about 2.4 percent of the total geographical area of the world.

2.India has a land boundary of about 15,200 km and the total length of the coastline of the mainland including Andaman and Nicobar and Lakshadweep is 7,516.65 km.

3. The Indian landmass has a central location between the East and West Asia. India is a southward extension of the Asian continent.

4. India occupies an important strategic position in South Asia. India has 29 states and 7 Union Territories. The neighbouring countries of India are-Pakistan, Afghanistan, China, Nepal, Bhutan, Myanmar, Bangladesh, Sri Lanka and Maldives.

5. India has had strong geographical and historical links with her neighbours.

India Size and Location Class 9 CBSE Notes Important Terms

Longitude: It refers to the imaginary lines that bisect the globe through the North and South Poles the ones that run vertically, as opposed to the lines of latitude that run horizontally, parallel to the equator.

Latitude: The angular distance east or west on the earth’s surface, measured by the angle contained between the meridian of a particular place and some prime meridian, as that of Greenwich, England, and usually expressed in degrees.

Equator: The imaginary great circle around the earth’s surface equidistant from the poles and perpendicular to the earth’s axis of rotation. It divides the earth into the Northern Hemisphere and the Southern Hemisphere.

Mainland: A large continuous extent of land that includes the greater part of a country or territory, as opposed to offshore islands and detached territories.

Coastline: The land along a coast. A line that forms the boundary between the land and the ocean, or a lake.

Pass: A gap or break in high, rugged terrain such as a mountain ridge.

Merchandise: Goods to be bought and sold.

On this page, you will find NCERT Class 9 Geography Chapter 2 Notes Pdf free download. CBSE Class 9 Social Science Notes Geography Chapter 2 SST Physical Features of India will seemingly, help them to revise the important concepts in less time.

Physical Features of India Class 9 Notes Social Science Geography Chapter 2

CBSE Class 9 Geography Chapter 2 Notes Understanding the Lesson

1. The land of India displays great physical variation. Different geological periods have influenced her relief. Besides geographical formations, a number of processes such as weathering, erosion and disposition have created and modified the relief to its present form.

2. According to the theory of Plate tectonics, the upper part of the earth has been formed out of seven major and some minor plates. The movement of these plates are classified into three types- convergent boundary, divergent boundary and transform boundary.

3. The oldest landmass was a part of the Gondwana land. The Gondwana land included India, Australia, South Africa, South America and Antarctica as one single landmass.

4. Geologically, the Peninsular Plateau constitutes one of the ancient landmasses on the earth’s surface. The Himalayas and the Northern Plains are the most recent landforms.

5. The physical features of India can be grouped under six physiographic divisions-the Himalayan Mountains, the Northern Plains, the Peninsular Plateau, the Indian Desert, the Coasted Plains and the Islands.

6. The whole mountain system of Himalayas represents a very youthful topography with high peaks, deep valleys and fast-flowing rivers. The Himalayas consist of three parallel ranges in its longitudinal extent-The Great or Inner Himalayas or the Himadri, Himachal or lesser Himalayas and the Shivaliks.

7. Besides the longitudinal divisions, the Himalayas have been divided on the basis of regions from west to east-Punjab Himalayas, Kumaon Himalayas, the Nepal Himalayas and Assam Himalayas.

8. The Brahmaputra marks the easternmost boundary of the Himalayas known as the Purvachal or the eastern hills and mountains. The Purvachal comprises the Patkai hills and Naga hills, Manipur hills and the Mizo hills.

9. The Northern Plains are formed of alluvial deposits. The three major river systems of which the plain have been formed are-the Indus, the Ganga, and the Brahmaputra along with their tributaries.

10. The Northern plains are broadly divided into three sections-The Punjab plains, the Ganga plain and the Brahmaputra plain. These plains have diverse relief features. According to the variations in relief features, they can be divided into four regions.

11. The largest part of the Northern Plains is formed of older alluvium. They lie above the floodplains of the rivers and is known as The newer, younger deposits of the flood plains are called khadar.

12. The Peninsular plateau is composed of igneous and metamorphic rocks with gently rising hills and wide valleys. This plateau consists of two broad divisions, namely, the Central Highlands and the Deccan Plateau. The Deccan Plateau is a triangular landmass that lies to the south of the river Narmada.

13. The Western Ghats and the Eastern Ghats mark the western and the eastern edges of the Deccan plateau respectively. The Western Ghats are continuous and are higher than the Eastern Ghats.

14. The Great Indian desert lies towards the western margins of the Aravali Hills. It is an undulating sandy plain covered with sand dunes. This region receives very low rainfall.

15. The coastal plains of India are located along the Arabian Sea coast in the west and along the Bay of Bengal coast in the east. According to their location to the east or west of the peninsular plateau, they are a called-East coastal plain and West coastal plain.

16. India has two groups of Islands-The Lakshadweep Islands groups and the Andaman and Nicobar Islands. The Lakshadweep Islands groups lie close to the Malabar coast of Kerala and the Andaman and Nicobar Islands are located in the Bay of Bengal.

17. Different physiographic units highlights the unique features of each region. Each region complements the other and makes the country richer in its natural resources.

Physical Features of India Class 9 CBSE Notes Important Terms

Folding: A type of earth movement resulting from the horizontal compression of rock layers by internal forces of the earth along plate boundaries.

Faulting: A crack in the earth’s crust resulting from the displacement of one side with respect to the other.

Gondwana land: It is the southern part of the ancient supercontinent Pangea with Angara land in the northern part.

Tethys: The sedimentary rocks accumulated in the geosyncline.

Duns: The longitudinal valley lying between lesser Himalaya and the Shivaliks.

Alluvium: A deposit of clay, silt and sand left by flowing floodwater in a river valley or delta, typically producing fertile soil.

Doab: The term is made up of two words-‘do’ meaning two and ‘ab’ meaning water.

Distributaries: Branches of rivers that do not return to the mainstream after leaving it.

Terai: A wet, swampy and marshy region.

Kankar: The soil containing calcareous deposits.

Khadar: The newer, younger alluvium of the flood plains.

Bhangar: The older alluvium lying above the flood plains of the rivers and presenting a terrace like feature.

Central Highlands: The part of the Peninsular plateau lying to the north of the Narmada river covering a major area of the Malwa plateau.

Western Ghats: The western edges of the Deccan plateau.

Eastern Ghats: The eastern edges of the Deccan plateau.

Deccan Trap: The black soil area of the Peninsular plateau.

Barchans: Crescent-shaped dunes found in the desert regions.

Dune: A hill of loose sand built by wind or the flow of water.

Konkan: The northern part of the coast.

Kannad plain: The central stretch of level open land.

Coral polyps: Short-lived microscopic organisms, which live in colonies.

On this page, you will find Improvement in Food Resources Class 9 Notes Science Chapter 15 Pdf free download. CBSE NCERT Class 9 Science Notes Chapter 15 Improvement in Food Resources will seemingly help them to revise the important concepts in less time.

CBSE Class 9 Science Chapter 15 Notes Improvement in Food Resources

Improvement in Food Resources Class 9 Notes Understanding the Lesson

1. The population of India is more than one billion people, and it is still growing. So, the need of the hour is to increase the food production. This can be done by farming on more land. India is already intensively cultivated, so the only way out is to increase our production efficiency for both crops and livestock.

2. There is a need for sustainable practices in agriculture and animal husbandry to increase food production without degrading our environment and disturbing the balances maintaining it.

3. Types of Revolutions Related to Increase in Food Production

• Green revolution: increase in food grain production.
• White revolution: increase in milk production.
• Blue revolution: increase in fish production.
• Yellow revolution: increase in oilseed crops production.
• Golden revolution: increase in pulse production.

4. Kharif season crops: These are grown in rainy season from the month of June to October. Paddy, soyabean, pigeon pea, maize, cotton, green gram and black gram are kharif crops.

5. Rabi season crops: These are grown in winter season from November to April. Wheat, gram, peas, mustard and linseed are Rabi crops.

6. Msyor groups of activities for improving crop yields

• Crop variety improvement
• Crop production improvement
• Crop protection management

7. Hybridisation: A crossing between genetically dissimilar plants is called hybridisation.

8. Types of hybridisation

• Intervarietal: crossing between different varieties.
• Interspecific: crossing between two different species of the same genus.
• Intergeneric: crossing between different genera.

9. Ways of improving crop: Hybridisation, polyploidy, recombinant DNA technology, genetic manipulation, mutation breeding, etc.

10. Some of the factors for which variety improvement is done are

• Higher yield
• Improved quality
• Biotic and abiotic resistance
• Change in maturity duration
• Wider adaptability
• Desirable agronomic characteristics
• Higher yield
• Improved quality
• Biotic and abiotic resistance
• Change in maturity duration
• Wider adaptability
• Desirable agronomic characteristics

11. Nutrients
There are sixteen nutrients which are essential for plants. Carbon and oxygen supplied by air, hydrogen comes from water, and the other thirteen nutrients supplied by soil to plants.

12. Types of Nutrients:

• Macronutrients: The nutrients which are required in large quantities. They are six.
• Micronutrients: The nutrients which are required in small quantities. They are seven.

13. Manure
Manure is prepared by the decomposition of animal excreta and plant waste and contains a lot of organic matter which helps in enriching soil with nutrients and increasing soil fertility. It is classified on the basis of kind of biological material used as:

• Compost: Compost is prepared by decomposition of the farm waste material like livestock excreta (cow dung etc.), vegetable waste, animal refuse, domestic waste, sewage waste, straw, eradicated weeds, etc., in pits.
• Vermi-compost: The compost is called as vermicompost if it is prepared by using earthworms to hasten the process of decomposition of plant and animal refuse.
• Green manure: Green plants like sun hemp or guar are grown and then mulched by ploughing them into the soil prior to the sowing of the crop seeds to enrich the soil in nitrogen and phosphorus.

14. Fertilisers: They are commercially produced plant nutrients which supply nitrogen, phosphorus and potassium to soil in order to increase the crop yield.

15. Organic farming: It is a farming system which focuses on the minimal or no use of chemicals like fertilisers, herbicides, pesticides, etc., and with a maximum input of organic manures, recycled farm-wastes (straw and livestock excreta), use of bio-agents, etc.

16. Irrigation systems
Wells, canals, river lift system, tank, etc., are used for irrigation. Some new initiatives like rainwater harvesting and watershed management are being used. For this small check-dams are constructed to stop the rainwater from flowing and lead to an increase in ground water levels.

17. Cropping Patterns

• Mixed cropping: Growing two or more crops simultaneously on the same piece of land.
• Inter-cropping: Growing two or more crops simultaneously on the same field in a definite pattern.
• Crop rotation: Growing two or more crops on a piece of land in a pre-planned succession.

18. Crop Protection Management

Weeds: The unwanted plants in the cultivated field which compete for food, space and light with the crop plant and reduce the growth of the crop. For example, Xanthium (gokhroo), Parthenium (gajar ghas), Cyperinus rotundus (motha).

Weed control methods: Mechanical removal, spray of chemicals called weedicides and preventive methods like proper seed bed preparation, timely sowing of crops, intercropping and crop rotation.

Three ways in which insect pests attack the plants

• They cut the root, stem and leaf,
• They suck the cell sap from various parts of the plant, and
• They bore into stem and fruits.

19. Insect and Pest control methods: Spray of chemicals like insecticides, pesticides, use of resistant varieties and summer ploughing in which fields are ploughed deep in summers to destroy weeds and pests, crop rotation and cropping systems.

Ways to reduce loss during storage of grains

• Proper treatment and systematic management of warehouses.
• They include strict cleaning of the produce before storage,
• Proper drying of the produce first in sunlight and then in shade
• Fumigation using chemicals that can kill pests.

Animal Husbandry

• The scientific management of animal livestock is called animal husbandry.
  Cattle husbandry is done for two purposes: milk and draught labour for agricultural work.
• Two species of Indian cattle: Bos indicus of cows and Bos bubalis of buffaloes.
• Milch animals: Milk-producing females of cattle are called milch animals (dairy animals).
• Draught animals: Animals used for farm labour are called draught animals.
• Lactation period: The period of milk production after the birth of a calf is called lactation period. Milk
• production can be increased by increasing the lactation period.
• Exotic or foreign breeds of cow: Jersey, Brown Swiss are selected for long lactation periods while Local breeds of cow: Red Sindhi, Sahiwal show excellent resistance to diseases.

Food requirements of dairy animals:
Their food requirements are of two types:

• Maintenance requirement, which is the food required to support the animal to live a healthy life.
• Milk producing requirement, which is the type of food required during the lactation period.

Two types of feed for animals are

• Roughage, which is largely fibre.
• Concentrates, which are low in fibre and have high levels of proteins and other nutrients.

20. Poultry farming: It is undertaken to raise domestic fowl called layers for egg production and the broilers for chicken meat.

21. Indigenous breed: Aseel; Exotic or foreign breed: Leghorn

Desirable traits of poultry

• number and quality of chicks;
• dwarf broiler parent for commercial chick production;
• summer adaptation capacity/tolerance to high temperature;
• low maintenance requirements;
• reduction in the size of the egg-laying bird with ability to utilise more fibrous cheaper diets formulated using agricultural by-products.

22. Fish production: It includes the finned true fish as well as shellfish such as prawns and molluscs.

23. Two ways of obtaining fish

• Capture fishery: Fish are obtained from natural resources in capture fishery.
• Culture fishery: Fish farming is called culture fishery.

24. Types of fish: The fish can be classified according to the water source from which they are obtained as Freshwater fishery and Marine fishery.

25. Inland or freshwater fisheries: Fresh water resources include canals, ponds, reservoirs and rivers. Example- Catla, Rohu, etc.

26. Marine fisheries: Marine fishery resources include 7500 km coastline and the deep seas beyond it. Some marine fish varieties are pomphret, mackerel, tuna, sardines and Bombay duck. Fishes like mullets, bhetki and pearl spots; shellfish such as prawns, mussels and oysters as well as seaweed are of high economic value.

27. Composite fish culture systems: A combination of five or six fish species is used in a single fish pond in the composite fish culture system. The selected species do not compete for food among them as they have different types of food habits.

28. The types of fishes used are:
Catlas are surface feeders, Rohus feed in the middle-zone of the pond, Mrigals and Common Carps are bottom feeders, and Grass Carps feed on the weeds. As a result, the food available in all the parts of the pond is used.

29. Bee Keeping: It is done for obtaining honey which is used in many medicinal preparations and bee wax which is used in cosmetics.

30. Local variety of bee: Apis cerana indica, commonly known as the Indian bee, Apis dorsata, the rock bee and Apis florae, the little bee.

31. Italian bee variety: Apis mellifera is the Italian variety of bee. It has the following advantages:

• They have high honey collection capacity.
• They sting somewhat less.
• They stay in a given beehive for long periods, and breed very well.

Class 9 Science Chapter 15 Notes Important Terms

Green revolution: The increase in food grain production is called green revolution.

White revolution: The increase in milk production is called white revolution.

Blue revolution: The increase in fish production is called as blue revolution.

Yellow revolution: The increase in oilseed crops production is called yellow revolution.

Golden revolution: The increase in pulse production is called golden revolution.

Kharif season crops: These crops are grown in rainy season from the month of June to October. Rabi season crops: These crops are grown in winter season from November to April.

Hybridisation: A crossing between genetically dissimilar plants is called as hybridisation. Macronutrients: The nutrients which are required in large quantities.

Micronutrients: The nutrients which are required in small quantities.

Manure: Manure is prepared by the decomposition of animal excreta and plant waste and helps in increasing soil fertility.

Vermi-compost: The compost prepared by using earthworms to hasten the process of decomposition of plant and animal refuse.

Fertilisers: They are commercially produced plant nutrients which supply nitrogen, phosphorus and potassium to soil in order to increase the crop yield.

Organic farming: The farming system which focuses on the minimal or no use of chemicals like fertilisers, herbicides, pesticides etc. and with a maximum input of organic manures, recycled farm- wastes (straw and livestock excreta), use of bio-agents, etc.

Mixed cropping: Growing two or more crops simultaneously on the same piece of land.

Inter-cropping: Growing two or more crops simultaneously on the same field in a definite pattern.

Crop rotation: Growing two or more crops on a piece of land in a pre-planned succession.

Weeds: The unwanted plants in the cultivated field which compete for food, space and light with the crop plant and reduce the growth of the crop.

Animal husbandry: The scientific management of animal livestock is called animal husbandry. Milch animals: Milk-producing females are called milch animals (dairy animals).

Draught animals: Animals used for farm labour are called draught animals.

Lactation period: The period of milk production after the birth of a calf is called lactation period. Capture fishing: Fish obtained from natural resources is capture fishing.

Culture fishery: Fish farming is called culture fishery.

Composite fish culture systems: A combination of five or six fish species is used in a single fish pond in the composite fish culture system.

On this page, you will find Natural Resources Class 9 Notes Science Chapter 14 Pdf free download. CBSE NCERT Class 9 Science Notes Chapter 11 Natural Resources will seemingly help them to revise the important concepts in less time.

CBSE Class 9 Science Chapter 14 Notes Natural Resources

Natural Resources Class 9 Notes Understanding the Lesson

1. Natural resource: Any substance or material derived from nature that humans can use for their benefit. The resources on the Earth are land, water and air.

2. The outer crust and the upper mantle of the Earth is called lithosphere.

3. All the water on, under and above the surface of the Earth comprises the hydrosphere.

4. The blanket of air that covers the whole of the Earth is called atmosphere.

5. The atmosphere, the hydrosphere and the lithosphere interact to constitute biosphere which is the life-supporting zone of the Earth i.e., living things are found where these three exist.

6. The two components of the biosphere are

• Biotic component: comprises of living things.
• Abiotic component: comprises of non-living things like air, water and soil.

7. Air is a mixture of gases like nitrogen, oxygen, carbon dioxide and water vapour.

8. Carbon dioxide constitutes up to 95-97% of the atmosphere on planets—Venus and Mars.

9. Carbon dioxide is produced by activities like:

• Respiration in eukaryotic cells and prokaryotic cells.
• Combustion (it includes burning of fuels to get energy and forest fires).

10. Carbon dioxide is ‘fixed’ in two ways:

• By green plants during photosynthesis to make glucose.
• Carbonates dissolved in sea water are used by many marine animals to make their shells.

11. Role of atmosphere:

• It keeps the average temperature of the Earth fairly constant.
• It prevents the sudden increase in temperature during the daylight hours.
•  It slows down the escape of heat into outer space during night.

12. The temperature ranges from -190°C to 110°C in the moon as it does not have atmosphere.

13. Changes occur in the atmosphere due to:

• Heating of air
• The formation of water vapour.

14. Convection currents are set up in air when the atmosphere gets heated from below by the radiation that is reflected back by the land or water bodies.

15. During the day in the coastal regions, the air above the land gets heated faster and warm air being lighter rises up thereby creating a region of low pressure. The air over the sea then moves towards the area of low pressure. The movement of air from one region to the other creates winds. At night, water cools down slower than the land, so the air above water would be warmer than the air above the land. This causes air over the land to move towards the region of low pressure over water.

16. Two main factors which influence winds:

• the rotation of the Earth
• the presence of mountain ranges in the paths of wind

17. Heating of water bodies and the activities of living organisms result in evaporation of water and formation of water vapour.

18. As the air containing water vapour rises up, it expands and cools to condense in the form of tiny droplets. This condensation of water is facilitated if particles like dust and other suspended particles act as the ‘nucleus’ for these drops to form around. Once the water droplets are formed, they grow bigger by the ‘condensation’ of these water droplets. These drops grow big and heavy and then fall down in the form of rain.

19. If the temperature of air is low, then precipitation may occur in the form of snow, sleet or hail.

20. The prevailing wind patterns in an area decide the rainfall patterns there.

21. The rains in India are mostly brought by the southwest or north-east monsoons.

22. The burning of fossil fuels like coal and petroleum releases:

• Oxides of nitrogen and sulphur which dissolve in rain to give rise to acid rain.
• Suspended particles which are unburnt carbon particles or substances called hydrocarbons. In cold weather conditions, high levels of these pollutants cause visibility to be lowered when water condenses out of air. This phenomenon is known as smog.

23. Most of the water on the Earth’s surface is found in seas and oceans and is saline.

24. Fresh water is found frozen in the ice-caps at the two poles and on snow covered mountains.

25. The underground water and the water in rivers, lakes and ponds is also fresh.

26. Water is essential for the various metabolic and the biochemical processes taking place in a living organism.

27. Water pollution is caused due to:

• Addition of undesirable substances (like pesticides, fertilisers, disease causing organisms)
• removal of desirable substances (like dissolved oxygen)
• Change in temperature of water (e.g., addition of hot water released from industries into rivers or the water released from dams into rivers which would be colder than water on the surface).

28. The outermost layer of our Earth is called the crust and the minerals found in this layer supply a variety of nutrients to life-forms.

29. Soil is a mixture of minerals, organic matter, gases, liquids, and various organisms that together support life on Earth.

30. Soil is formed due to various physical, chemical and biological processes which result in breakdown of rocks into fine particles of soil over millions of years. The formation of soil occurs due to factors and processes like Sun, water, wind, living organisms and lichens.

31. Removal of useful components from the soil and addition of undesirable substances into it which adversely affect the fertility of the soil and kill the diversity of organisms that live in it, is called soil pollution.

32. Constant recycling of nutrients and materials occurs between the biotic and the abiotic components in an ecosystem. The pathway by which a chemical substance moves through biotic and abiotic components of the Earth is called biogeochemical cycle.

33. Nitrogen gas constitutes 78% of our atmosphere and is a part of many molecules like proteins, nucleic acids (DNA and RNA) and some vitamins which are essential for life.

34. Legumes (like pulses) have nitrogen-fixing bacteria in their root nodules which convert the nitrogen molecules into nitrites and nitrates.

35. The high temperatures and pressures created in the air during lightning convert nitrogen into oxides of nitrogen which dissolve in water to give nitric and nitrous acids. They can be utilised by various living organisms when they fall on land along with rain.

36. The phenomenon in which the incoming sunlight is allowed to pass through the atmosphere but heat radiated back from the planet’s surface is trapped by the gases like carbon dioxide, water vapour and methane present in the atmosphere is called as greenhouse effect.

37. Increase in percentage of the gases like carbon dioxide and methane prevents escape of heat from the Earth. Greenhouse effect is responsible for the increase in average temperature worldwide and is causing global wanning.

38. Ozone is a molecule containing three atoms of oxygen with a formula of 03 and contains three atoms of oxygen. It is a poisonous gas but does not harm us as it is present in the upper reaches of the atmosphere. It plays an important role as it absorbs harmful radiations from the Sun which can harm living organisms.

39. Ozone layer is getting depleted due to the use of CFCs. CFCs are carbon compounds having both fluorine and chlorine which are very stable and not degraded by any biological process. These react with the ozone molecules and result in its reduction.

40. An ozone hole caused due to the reduction of ozone molecules has been discovered above the Antarctica.

Class 9 Science Chapter 14 Notes Important Terms

Natural resource: Anything that comes from nature and can be used by humans for various purposes is called a natural resource.

Lithosphere: The outer crust and the upper mantle part of the Earth is called the lithosphere.

Hydrosphere: All the water on, under and above the surface of the earth comprises the hydrosphere.

Atmosphere: The blanket of air that covers the whole of the Earth is called atmosphere.

Biosphere: The region comprising of lithosphere, hydrosphere and the atmosphere which can sustain life or living organisms is called biosphere.

Components of biosphere: The two components of biosphere are biotic (living) component and abiotic (non living) component.

Wind: Moving air is called wind.

Air pollution: The addition of undesirable substances in air which adversely affect its physical, chemical or biological characteristics is called air pollution.

Pollutant: The undesirable substances added to air, water or land which pollutes them is called pollutant.

Biodiversity: The variety of life forms present on Earth constitutes its biodiversity.

Water pollution: The addition of undesirable substances in water which adversely affect its physical, chemical or biological characteristics is called water pollution.

Biogeochemical cycle: The pathway by which a chemical substance moves through biotic and abiotic components of the Earth is called biogeochemical cycle.

Greenhouse effect: The phenomenon in which the incoming sunlight is allowed to pass through the atmosphere but heat radiated back from the planet’s surface is trapped by the gases like carbon dioxide, water vapour and methane present in the atmosphere is called greenhouse effect.

Ozone: The triatomic molecule of oxygen with formula 03 which prevents the harmful UV radiation of the Sun from reaching the earth’s surface.