NCERT CLASS 9 BOOKS

 Class 9 English Beehive

Class 9 English Moments 

Class 9 English Words and Expressions 1 

Class 9 Health and Physical Education 

Class 9 हिन्दी कृतिका 

Class 9 हिन्दी क्षितिज  

Class 9 संचयन 

Class 9 स्पर्श 

Class 9 अभ्यासवान भव 

Class 9 शेमुषी 

Class 9 व्याकरणवीथि: 

Class 9 Mathematics 

Class 9 Science 

Class 9 Social Science Contemporary India-I 

Class 9 Social Science Democratic Politics-I 

Class 9 Social Science Economics 

Class 9 Social Science India and the Contemporary World I

Class 12 Biology in English

 

CLASS 12 BIOLOGY FRONT MAIN PAGE

CLASS 12 BIOLOGY CHAPTER 1 REPRODUCTION IN ORGANISMS 

CLASS 12 BIOLOGY CHAPTER 2 SEXUAL REPRODUCTION IN FLOWERING PLANTS

CLASS 12 BIOLOGY CHAPTER 3 HUMAN REPRODUCTION 

CLASS 12 BIOLOGY CHAPTER 4 REPRODUCTIVE HEALTH

CLASS 12 BIOLOGY CHAPTER 5 PRINCIPLE OF INHERITANCE AND VARIATION 

CLASS 12 BIOLOGY CHAPTER 6 MOLECULAR BASIS OF INHERITANCE

CLASS 12 BIOLOGY CHAPTER 7 EVOLUTION 

CLASS 12 BIOLOGY CHAPTER 8 BIOLOGY IN HUMAN WELFARE

CLASS 12 BIOLOGY CHAPTER 9 STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION 

CLASS 12 BIOLOGY CHAPTER 10 MICROBES IN HUMAN WELFARE

CLASS 12 BIOLOGY CHAPTER 11 UNIT IX BIOTECHNOLOGY 

CLASS 12 BIOLOGY CHAPTER 12 BIOTECHNOLOGY AND ITS APPLICATIONS

CLASS 12 BIOLOGY CHAPTER 13 ORGANISMS AND POPULATIONS

CLASS 12 BIOLOGY CHAPTER 14 ECOSYSTEM 

CLASS 12 BIOLOGY CHAPTER 15 BIODIVERSITY AND CONSERVATION

CLASS 12 BIOLOGY CHAPTER 16 ENVIRONMENTAL ISSUES 

Class 12 Chemistry In English

 

Class 12 Chemistry Unit 1 Solid State

Class 12 Chemistry Unit 2 Solutions 

Class 12 Chemistry Unit 3 Electrochemistry

Class 12 Chemistry Unit 4 Chemical Kinetics 

Class 12 Chemistry Unit 5 Surface Chemistry

Class 12 Chemistry Unit 6 General Principles and Processes of Isolation of Elements 

Class 12 Chemistry Unit 7 The p Block Elements 

Class 12 Chemistry Unit 8 The d and f Block Elements 

Class 12 Chemistry Unit 9 Coordination Compounds 

Class 12 Chemistry Unit 10 Haloalkanes and Haloarenes 

Class 12 Chemistry Unit 11 Alcohols Phenols and Ethers 

Class 12 Chemistry Unit 12 Aldehydes Ketones and Carboxylic Acids 

Class 12 Chemistry Unit 13 Amines 

Class 12 Chemistry Unit 14 Biomolecules 

Class 12 Chemistry Unit 15 Polymers 

Class 12 Chemistry Unit 16 Chemistry in Everyday Life 

 

Class 12 Physics In English

 Class 12 Physics Chapter 1 ELECTRIC CHARGES

Class 12 Physics Chapter 2 ELECTROSTATIC 

Class 12 Physics Chapter 3 CURRENT 

Class 12 Physics Chapter 4 MOVING CHARGES 

Class 12 Physics Chapter 5 MAGNETISM AND MATTER 

Class 12 Physics Chapter 6 ELECTROMAGNETIC INDUCTION 

Class 12 Physics Chapter 7 ALTERNATING CURRENT 

Class 12 Physics Chapter 8 ELECTROMAGNETIC WAVES 

Class 12 Physics Chapter 9 RAY OPTICS AND OPTICAL INSTRUMENTS 

Class 12 Physics Chapter 10 WAVE OPTICS 

Class 12 Physics Chapter 11 DUAL NATURE OF RADIATION AND MATTER 

Class 12 Physics Chapter 12 ATOMS 

Class 12 Physics Chapter 13 NUCLEI 

Class 12 Physics Chapter 14 Semiconductor Electronics Materials Devises and Simple Circuits 

Class 12 Physics Chapter 15 Communication System 

Class 12 Physics Answers Part 1 

Class 12 Physics Answers Part 2 

Our Earth

Our Earth

Inside our Earth

The earth is about 460 crore year old. Its surface has been going changes throughout the years. WE still have very limited information what is inside our Earth.

        A detailed study of the interior of the earth is done by Geologists. An elementary knowledge about the Earth’s structure is necessary to understand the nature of changes that take place on the surface of the Earth.

        It is impossible to reach the center of the Earth because the temperature inside increases with the increase in depth. The temperature at the center is estimated to be about 5000⁰C. Thus, it is not possible to access direct information about the interior of the Earth.

Structure of the Earth:

Structure of the Earth

On the basis of varying density and other physical and chemical properties of rocks, the Earth can be divided into three concentric layer-crust, mantle and core. This arrangement can be compared to an onion with its layers one inside the other.

        The Crust:  

The Crust

The outermost shell, called the crust or lithosphere is the thinnest layer. Its average thickness varies from 5 to 40 km. The average thickness f the crust on an average is about hand, the continental crust is less denser than the oceanic crust because it is made of light and rock layer.

        The chief mineral constituents of the continental crust are silica and alumina. It is also called sial (si-silica and al-alumina).

The oceanic crust consists mainly of silica and magnesium. It is called (si-silica and ma- magnesium).and nickel. It is also called nife (ni-nickel and fe-iron). The heavy metals and plenty of iron explain the cause of Earth’s magnetism.

        The Mantle:  

The Mental

The mantle or the mesosphere is the second layer of the Earth. It is located beneath the crust and extends up to the core of the Earth. The average thickness of the mantle is 2900 km and it is made up of rocks that are far denser that the crust. The mantle is divided into three layers, depending on temperature and pressure, which cause the racks to be solid or semi-solid. The temperature of the mantle is extremely high since it contains molten magma which comes to the surface during volcanic eruptions as lava. Iron is the constituents of the mantle.

        The Core:  

The Core

The innermost layer of the Earth is called the core or the barysphere.  Being composed of mostly metal, it is also known as the metallic core. It is separated from the mantle by a boundary. The core is also divided into two parts. The outer core is composed of iron and is in liquid state. The inner core is composed of iron and nickel. It is also called nife ( ni-nickel and fe-iron). The heavy metals and plenty of iron explain the cause of the Earth magnetism.  

 Rocks and Minerals:

Rocks

 

A rock can be defined as an aggregate of minerals. Earth is made up of rocks and minerals. The rocks forming the crust of hand position of the Earth crust can be called as rocks. They make up most of the soft materials of the lithosphere. It has no definite composition. Most of the rocks are mixture of various minerals in different proportions. Rocks may be hard or soft

Mineral

                       A mineral is a naturally occurring substance having a definite chemical composition and physical properties. A rocks having a large proportion of a single mineral so that the mineral concerned can be extracted economically from it, is called an ore of that mineral. Magnetite, an ore of iron is an example of such rocks.

Types of rocks:

Types of rocks

 

Rocks are usually classified into three main groups, depending upon the way in which they have been formed.

Igneous rocks:  

Igneous rocks

These rocks are also known as primary rocks because they are believed to be the first rocks formed on the Earth. All other rocks are ultimately derived from igneous rocks. They covered the large percentage of the Earth’s crust. Before formation of the crust, magma was in liquid state. Its upper layer cooled and became surface of the Earth which gave rise to these rocks. These rocks continue to be formed even today. Molten material in the interior of the Earth is known as magma. When it comes out of the cracks in 100 km deep layer through volcano, it is called lava which on cooling forms igneous rocks on surface on the Earth. When these rocks are formed on the Earth, they are called extrusive rocks. Examples of such rocks are basalt and rhyolite. Intrusive rocks are those igneous rocks beneath the Earth’s surface.

 Igneous rocks have the following characteristics:

• These rocks are hard and compact.
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• These rocks do not occur in distinct beds or stratas.
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• These rocks do not have remains of animals or plants.
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• These rocks do not allow water to percolate through them.
• 
  
• Other types of rocks are formed from igneous rocks.
• 
  
• Valuable minerals such as iron, gold, silver and aluminum are found in these rocks.

Sedimentary rocks: 

Sedimentary rocks

 sedimentary rocks are formed consolidation of sediments deposited in water bodies like rivers, lakes and seas. The sediments are derived by denudation of the rocks by agents of erosion like rivers, glaciers, winds and waves. These agents of erosion carry the eroded particles of rocks to the water bodies and deposit them there.

                       Such deposited material is called loose particles of gravel, sand, silt and clay in various proportions. Over a period of time, a significant thickness of sediments accumulates and it gets consolidated or compacted to form hard rocks. These are sedimentary rocks. 

                       Sedimentary rocks are formed either mechanically (sandstone), chemically (salt) or organically (coal). These rocks are the most widespread and cover about 75 percent of the total land area of the Earth.

Sedimentary rocks have the following characteristics:

1. These rocks are softer than igneous rocks.

2. These rocks have horizontal layers, arranged one above the other.

3. These rocks are mostly formed under water and have marks of waves and mud-cracks.

4. These rocks also contain remain animals and plants, called fossils between the layers.

5. The important examples are sandstone, limestone and coal.

Metamorphic rocks: 

Metamorphic rocks

 As the name suggests, metamorphic rocks are rocks which have changed their state from their state from their earlier form. They are formed by subjecting any rocks type (including previously formed metamorphic rock) to different temperatures and pressures condition than those in which the original rock was formed. These temperatures and pressures condition than those in which the original rocks was formed. These temperatures and pressures are so high that they change the original mineral into other mineral types or formed by various natural processes like recrystallization etc.

Metamorphic rocks have the following characteristics.

1. These rocks after changes remain in their original position.

2. They are very hard and have a very high specific gravity.

3. These rocks do not have empty spaces in them.

Uses of Rocks and Minerals

1. In ancient times, rocks were used to make tools and weapons.

2. Rocks are widely used in the construction of roads, houses and buildings.

3. Minerals like coal and petroleum provide the sources of power.

4. Chemicals found in some sedimentary rocks are used to make fertilizers.

5. Soil is formed from rocks.

Rock Cycle

Rock Cycle

 

                The rocks cycle in the simple term can be described as the process of transformation of one rock form to another. It is a fundamental concept in geology that describes the change among the three main rock types- sedimentary, metamorphic and igneous. These changes do not happen in a day or even year but take hundreds of years.

To understand the process, let us see the example below:

1. Igneous rocks as you studied above are formed by the cooling of molten magma which comes out through volcanoes.

2. The various agents of weathering like the temperature fluctuation, the flow of wind and water, action of plants and animals all cause erosion of the rocks and these igneous rocks keep breaking and cracking.

3. The broken pieces of rocks which may be as small as pebbles and fine sand keeps shifting and get moved by natural transportation in basins and lower regions and gradually form sedimentary rocks.

4. The layers keep forming over the sedimentary rocks and those which get buried deeper, again get subjected to the pressures and the heat of the Earth and change their state to the metamorphic rocks.

5. Similarly the intrusive rocks under the Earth surface are also subjected to heat and pressure and they change their state to the metamorphic rocks.

6. The metamorphic rocks again melt due to heat and pressures inside the Earth and mix into the existing magma inside the Earth and thus the cycle continues.

Class 12 Math In English

Class 12 Math Chapter 1 Relations and Functions

Class 12 Math Chapter 2 INVERSE TRIGONOMETRIC FUNCTIONS

Class 12 Math Chapter 3 Matrices

Class 12 Math Chapter 4 Determinants 

Class 12 Math Chapter 5 Continuity and Differentiability

 Class 12 Math Chapter 6 Application of Derivatives

Class 12 Math Chapter 7 Integrals 

Class 12 Math Chapter 8 Application of Integrals 

Class 12 Math Chapter 9 Differential Equations 

Class 12 Math Chapter 10 Vector Algebra 

Class 12 Math Chapter 11 Three Dimensional Geometry 

Class 12 Math Chapter 12 Linear Programming 

Class 12 Math Chapter 13 Probability 

Class 12 Math Answer-1 

CLass 12 Math Answer-2 

NATURAL VEGETATION AND WILDLIFE

 

NATURAL VEGETATION

AND

WILDLIFE

NATURAL VEGETATION  AND  WILDLIFE

 The Earth is the home of human being and other living organisms. This is possible due to the presence of favorable living condition which makes up their environment.

Environment: The term environment refers to the surrounding organisms within which a person, animal or plants exist. It is a combination of natural and human-made phenomena. Natural environment means both biotic and abiotic condition existing on Earth. Human environment refers to activities, creatures and interactions among different human beings.

NATURAL VEGETATION  AND  WILDLIFE

The natural elements such as mountains, rivers, vegetation, animals, etc. are created by nature. This is called natural environment. It includes the biotic and abiotic components.

       The human-made elements, such as agriculture, industries, settlement, means of transport, etc. are created by human beings. Therefore, it is called human-made environment. Human beings developed these features to live comfortably in their environment.

NATURAL VEGETATION  AND  WILDLIFE

The two types of environments interact with one other. They change in course of time from place to place due to natural processes and human activities.

Natural Environment:

Natural environment of an organism consists of those element that a provided by nature. The natural environment is made up of two kinds of components.

(i). Biotic components and

(ii). Abiotic (Non-living) components.

Let us briefly discuss them.

Biotic components: The biotic components comprise living beings like micro-organisms, plants and animals including man. This is also known as living or biological environment.

NATURAL VEGETATION  AND  WILDLIFE

Abiotic (Non-living) components: The Abiotic components comprise inorganic or non0livings things in the environment. Based on the physical state and characteristics, they are divided into:

NATURAL VEGETATION  AND  WILDLIFE

 Lithosphere:

The solid crust of rocks forming the surface of the Earth is called lithosphere. The word ‘litho’ means rocks or stones and ‘sphere’ means domain, so the term lithosphere can be described as ‘rocksphere’.

NATURAL VEGETATION  AND  WILDLIFE

 Lithosphere has an average thickness of about 100km. It is irregular in shape and not like smooth like a table top. It includes the various land-forms such as mountain, plains, plateaus, valleys etc. The part of the ocean floor is also uneven and not smooth surface. Lithosphere provides us mineral wealth, forest, grassland, agriculture land and land for human settlements.

Hydrosphere:

The hydrosphere is the part of the Earth’s surface covered by water. The water on Earth found in ocean, seas, rivers, lakes and streams etc. and in the form of ice and snow together make the hydrosphere. It occupies a major part of the Earth’s surface and has an importance of its own.

NATURAL VEGETATION  AND  WILDLIFE

More than 70% of Earth’s surface is covered with water. We cannot imagine life on Earth without water. Water is essential for all living organisms.

Atmosphere:

The Earth is a unique planet. Its capacity to support life makes it different from all other planets. The Earth is surrounded by an envelope of air which is called atmosphere.

NATURAL VEGETATION  AND  WILDLIFE

The atmosphere extends to about 1,000 km from the surface of the Earth.

       The layer of air which surrounds the Earth is a mix of gases which change with altitude. The gravity of the Earth holds the atmosphere around it. The atmosphere also has dust and water vapor. Changes of the atmosphere affect weather and climate. The atmosphere also works as a shield of the Earth to protect it from the harmful rays and scorching heat of the sun.

Biosphere:

The three spheres-lithosphere, hydrosphere and atmosphere meat to from a narrow zone of interaction, the biosphere, which supports life. Therefore, it includes the biotic and abiotic elements.

NATURAL VEGETATION  AND  WILDLIFE

Biosphere is a unique component of the Earth. Outside the limits of biosphere, no life is possible. Biosphere is a beautiful part of the Earth which consists of a great variety of flora and fauna. Other planets do not have biosphere. Each organism in the biosphere has central limiting condition for its growth and survival.

NATURAL VEGETATION  AND  WILDLIFE

The types of planets and animals found in a particular region are related to the prevailing physical environment, known as habitat. All organisms living in a particular habitat, depend on one-another. All organism in the biosphere interact which physical environment and which one-another.

Ecosystem:

NATURAL VEGETATION  AND  WILDLIFE

It is a system formed by the interaction of all living organisms with each other and with the physical and chemical factor of the environment in which they live. All plants, animals and human being depend on each other and on the immediate surroundings of natural environment. There could be different ecosystems in different environments like deserts, mountains, dense forests, grass lands, rivers, and oceans and even in ponds.

NATURAL VEGETATION  AND  WILDLIFE

Energy is transferred from one living thing to other in the form of various food chains and many different food chains like up to form food webs. All the food webs are delicately branched. So, if one like in the web is destroyed, all the other organisms will be affected.

Human Environment:

NATURAL VEGETATION  AND  WILDLIFE

Human beings are part of the environment in which they live. They are, to an extent, influenced by the environment. They are also able to depot and modify the environment according to their needs. With scientific and technological advancement, they have succeeded in controlling and dominating nature.

NATURAL VEGETATION  AND  WILDLIFE

The interaction of human being with the environment is complex in nature. It varies from place to place and from time to time.

Human-Environment Interaction:

In spite of all the development, the physical environment still provides human being with their material needs.The primary activities-farming, fishing, forestry and mining-still provide food and raw materials, without which advanced socialites cannot survive and progress.

NATURAL VEGETATION  AND  WILDLIFE

Human being and their activities also pose the greatest danger to the environment. Right From the dawn of human civilization, people have not only used nature for their existence and fulfillment of needs, but also exploited and misused it to a certain extent. 

Thus, they have disturbed the natural branches of the environment.