Part-1

Question 1

What is Geography?

Answer 1

1. The term geography was first devised by Eratosthenes, a Greek scholar (276-194 BC.)
2. Geography is a discipline of the combination of spatial synthesis and temporal synthesis.
3. According to geography, Earth is described as the abode of human beings.
4. Landforms provide the foundation on which anthropogenic activities are placed.
5. The plains are used for agriculture.
6. Plateaus provide a platform for minerals and forest.
7. Mountains make available space for meadows, forests, tourist spots, etc. They are regarded as the sources of rivers.

Question 2

Branches of Geography

Answer 2

1. Physical Geography
2. Human Geography
3. Biogeography

Question 3

Physical Geography

Answer 3

1. Geomorphology is a branch of Geography dealing with the study of landforms, the formation of landforms, and associated courses.
2. Climatology includes the study of atmosphere structure, elements of weather, climate, climatic types and climatic regions.
3. Hydrology deals with the study of water present on the surface of the earth comprising oceans, rivers, lakes and other water bodies, its influence on various life forms on earth and allied activities.
4. Soil Geography is to study the courses of soil formation, types of soil, fertility status of soils, soil distribution and utilization.

Question 4

Human Geography

Answer 4

1. Social/Cultural Geography covers the study of society and the spatial dynamics of society and the cultural aspects caused by society.
2. Population Geography encompasses the population growth, density, distribution, migration, sex ratio and occupational structure, and so on.
3. Settlement Geography deals with the features of urban and rural settlements.
4. Economic Geography is related to people’s economic activities comprising agriculture, industry, services, trade, transport, infrastructure, etc.
5. Historical Geography deals with the historical processes by which space gets organised. The geographical features also go through temporal changes; these are the issues of historical geography.
6. Political Geography is the study of the spatially unbalanced results of political courses and the various manners in which political processes are themselves influenced by spatial structures.

Question 5

Biogeography

Answer 5

• The interface between human geography and physical geography has led to the progress of Biogeography which contains:

1. Ecology and Ecosystem deal with the scientific study of the habitats features of species.
2. Plant Geography which deals with the spatial structure and order of natural vegetation in their environments.
3. Zoo Geography which is concerned with the spatial patterns as well as geographic features of various fauna and their habitats.

Question 6

Earth – Origin & Evolution

Early Theories

Answer 6

Nebular Hypothesis

• Immanuel Kant, a German philosopher gave this theory.
• In 1796, a mathematician Pierre-Simon Laplace reexamined it.
• According to this hypothesis, the planets were moulded out of a cloud of material associated with a young sun, which was rotating slowly.

Binary theories

• As per these theories, the sun had a companion.

Revised Nebular Hypothesis

• Revised Nebular Hypothesis was propounded by Carl Weizascar in Germany and Otto Schmidt in Russia.
• They regarded that a solar nebula surrounded the sun and that the nebula comprised of chiefly hydrogen, helium and something called dust.
• The collision of particles and the friction caused a disk-shaped cloud to be formed and then the planets were created via the accretion process.

Question 7

Modern theories of evolution

Answer 7

Big Bang Theory

• Alternatively called the expanding universe hypothesis.
• As per this theory, in the beginning, all matter or substance forming this universe existed at one place as a tiny ball. This tiny ball had an extremely small volume, infinite density and temperature.
• At the Big Bang, this ball blasted fiercely and forcefully and started a substantial process of expansion which continues to this day.
• Now it is accepted that this event took place 13.7 billion years ago.

Question 8

Formation of Planets

Answer 8

The following are regarded as the stages in the planets’ development:

1. The stars are localised gas lumps inside a nebula.
2. A core to the gas cloud as well as a spinning disc of dust and gas are created because of the gravitational force within the lumps.
3. After this, the cloud of gas condenses and the matter over the core is changed into tiny rounded objects.
4. These small round objects develop into what are called planetesimals by a cohesion process.
5. The smaller objects start forming larger bodies by colliding with one another and they stick together because of gravitational force.
6. In the last stage, these large number of small planetesimals aggregate to develop into a smaller number of large bodies called planets.

Question 9

Lightyear

Answer 9

1. It is a unit of astronomical distance which is equal to the distance light travels in one year.
2. A light year is a measure of distance and not of time.
3. Light travels at a speed of 300,000 km/second.

Question 10

Solar system

Answer 10

1. Solar system consists of eight planets.
2. Mercury, Venus, Earth, Mars, Jupiter, Uranus, Saturn and Neptune.
3. The inner planets are Mercury, Venus, Earth, and Mars.
4. After an asteroid belt come the outer planets, Jupiter, Saturn, Uranus, and Neptune.

Question 11

The Moon

Answer 11

• The moon is the only natural satellite of the earth.

Question 12

Evolution of the Earth

Answer 12

• The age of Earth is approximately one-third of the age of the universe.
• Earth formed around 4.54 billion years ago by accretion from the solar nebula.

Question 13

Lithosphere, Atmosphere, and Hydrosphere of the Earth

Answer 13

1. Lithosphere: The firm outer part of the earth, comprising of the crust and upper mantle.
2. Atmosphere: A layer of gases encircling a planet that is seized in place by the gravity of that body.
3. Hydrosphere: It is the collective mass of water found on, under, and above the surface of the earth.
4. The first stage of the evolution of Lithosphere, Atmosphere, and Hydrosphere is marked by the loss of primordial atmosphere.
5. In the second stage, the hot interior of the earth contributed to the evolution of the atmosphere.
6. Finally, the composition of the atmosphere was modified by the living world through the process of photosynthesis.
7. The present composition of earth’s atmosphere is chiefly contributed by nitrogen and oxygen.

Question 14

Geological Scale

Answer 14

Attached

Question 15

Structure of the Earth

Answer 15

1. The Crust
2. The Mantle
3. The Core

Question 16

The Crust

Answer 16

1. The crust is the outermost solid part of the earth.
2. It is fragile in nature.
3. The thickness of the crust varies under the oceanic and continental areas.
4. Oceanic crust is thinner as compared to the continental crust.
5. The continental crust is thicker in the areas of major mountain systems.
6. The crust made up of heavier rocks having a density of 3 g/cm3.
7. The kind of rock seen in the oceanic crust is basalt.
8. The mean density of material in the oceanic crust is 2.7 g/cm3.

Question 17

The Mantle

Answer 17

1. The portion of the interior beyond the crust is called the mantle.
2. It is in a solid state.
3. It has a density higher than the crust portion.
4. The thickness ranges from 10-200 km.
5. The mantle extends from Moho’s discontinuity to a depth of 2,900 km.
6. The asthenosphere is the upper portion of Mantle.
7. It is the chief source of magma that finds its way to the surface during volcanic eruptions.
8. The crust and the uppermost part of the mantle are called lithosphere.

Question 18

The Core

Answer 18

1. The core-mantle boundary is positioned at the depth of 2,900 km.
2. The inner core is in the solid state whereas the outer core is in the liquid state.
3. The core is made up of very heavy material mostly constituted by nickel and iron. Hence it is also called the “nife” layer.

Question 19

Continental Drift Theory

Answer 19

1. Continental drift theory was proposed by Alfred Wegener in 1912.
2. The theory deals with the distribution of the oceans and the continents.
3. According to Wegener’s Continental Drift theory, all the continents were one single continental mass (called a Super Continent) – Pangaea and a Mega Ocean surrounded this supercontinent. The mega ocean is known by the name Panthalassa.
4. The supercontinent was named Pangaea and the Mega-ocean was called Panthalassa.
5. According to this theory, the supercontinent, Pangaea, began to split some two hundred million years back.
6. Pangaea first split into 2 big continental masses known as Gondwanaland and Laurasia forming the southern and northern modules respectively.
7. Later, Gondwanaland and Laurasia continued to break into several smaller continents that exist today.

Question 20

Evidence supporting the Continental Drift Theory

Answer 20

1. The Matching of Continents (Jig-Saw-Fit)
2. Rocks of the Same Age across the Oceans
3. Tillite
4. Placer Deposits
5. Distribution of Fossils

1. The Matching of Continents (Jig-Saw-Fit)

• The coastlines of South America and Africa fronting each other have a remarkable and unique match.
• In 1964, Bullard created a map using a computer program to find the right fit of the Atlantic margin and it proved to be quiet.

2. Rocks of the Same Age across the Oceans

• The radiometric dating methods have helped in correlating the formation of rocks present in different continents across the ocean.
• The ancient rocks belts in the coast of Brazil match with those found in Western Africa.
• The old marine deposits found in the coasts of South America and Africa belong to the Jurassic Age. This implies that the ocean never existed before that time.

3. Tillite

• It is the sedimentary rock made from glacier deposits.
• The Gondwana system of sediments from India is recognized as having its counterparts in 6 different landmasses in the Southern Hemisphere.
• Counterparts of this series are found in Madagascar, Africa, Antarctica, Falkland Island, and Australia not to mention India.
• At the base, the system has thick tillite signifying widespread and sustained glaciation.
• Generally, the similarity of the Gondwana type sediments evidently shows that these landmasses had exceptionally similar origins.
• The glacial tillite gives a clear evidence for palaeoclimates and the drifting of continents.

4. Placer Deposits

• The presence of abundant placer deposits of gold along the Ghana coast and the complete lack of its source rocks in the area is a phenomenal fact.
• The gold-bearing veins are present in Brazil and it is evident that the gold deposits of Ghana in Africa are obtained from the Brazil plateau from the time when the two continents were beside each other.

5. Distribution of Fossils

• The interpretations that Lemurs occur in India, Africa and Madagascar led to the theory of a landmass named “Lemuria” connecting these 3 landmasses.
• Mesosaurus was a tiny reptile adapted to shallow brackish water.
• The skeletons of these creatures are found in the Iraver formations of Brazil and Southern Cape Province of South Africa.

Question 21

Force for Drifting

Answer 21

1. Wegener proposed that the movement accountable for the drifting of the continents was instigated by tidal force and pole-fleeing force.
2. The polar-fleeing force relates to the rotation of the earth.
3. The shape of earth
4. The second force that was proposed by Wegener, the tidal force.
5. Though, most of the scholars considered these forces to be totally insufficient.

Question 22

Earthquake

Answer 22

1. All natural earthquakes occur in the lithosphere.
2. Seismic waves studies offer a full picture of the layered interior.
3. An earthquake is, simply put, shaking of the earth’s crust.
4. It is caused due to the energy release, which triggers waves that travel in all directions.
5. The emanation of energy occurs along a fault.
6. A fault is a sharp break in the crustal rocks.
7. Rocks along a fault generally move in opposing directions.

Question 23

Types of Earthquakes

Answer 23

1. Tectonic earthquakes: These are produced due to sliding of rocks along a fault plane.
2. Volcanic earthquake: These are confined to areas of active volcanoes.
3. Collapse earthquake: The roofs of underground mines collapse causing minor tremors in the areas of intense mining activity.
4. Explosion earthquakes: These occur due to the explosion of chemical or nuclear devices.
5. Reservoir-induced earthquakes: These occur in the areas of large reservoirs.

Question 24

Causes of Earthquakes

Answer 24

1. It is caused due to the discharge of energy from faults and cracks in the crust of the earth.
2. A fault in the crust of Earth is essentially a sharp break in crustal rocks.
3. This energy release produces waves which travel in all directions.
4. The point where energy is released is called the focus or hypocentre. It is generally located at the depth of 60 km.
5. This causes a release of energy, and the energy waves travel in all directions.
6. The point where the energy is released is called the focus of an earthquake or hypocentre.
7. The point on the surface of the earth which is vertically above the focus is called epicentre. It is the first place to experience the waves.

Question 25

Body Waves

Answer 25

• Earthquake waves are of two types — body waves and surface waves.

P- Waves

1. P-waves are also known as the Primary waves. They are the first waves to arrive at the surface.
2. The characteristics of P-waves are like sound waves. They travel through all three mediums- solid, liquid and gas.
3. These waves have a tendency to vibrate parallel to the direction of wave propagation. This causes density differences in the material through which they travel.
4. These waves are responsible for elongating and squeezing of material.

S- Waves

1. S- Waves arrive after some time after the happening of Earthquake and they are called secondary waves.
2. A significant characteristic of these S-waves is that they travel only through a solid medium.
3. The direction of vibration of these S – wave is perpendicular to the direction of wave propagation, thereby creating crests and troughs in the material of their transmission.

Question 26

Shadow Zone

Answer 26

1. The shadow zone is the zone of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves.
2. The shadow zone results from P waves being refracted by the liquid core and S waves being stopped completely by the liquid core.
3. A zone between 105° and 145° from the epicentre was recognised as the shadow zone for both the waves types.
4. The entire zone beyond 105° does not receive S-waves.
5. The shadow zone of S-wave is larger than that of the P-waves.
6. The shadow zone of P-waves appears as a band around the earth between 105° and 145° away from the epicentre.

Question 27

Effects of earthquake

Answer 27

The following are the immediate hazardous effects of Earthquake:

• Shaking of ground
• Disparity in ground settlement
• Natural disasters like Tsunami, land slide, mud slides and avalanches
• Soil liquefaction
• Ground lurching and displacement
• Floods and fires
• Infrastructure collapse.

Question 28

Measurement of Earthquakes

Answer 28

All earthquakes are different in their intensity and magnitude. The instrument for measurement of the vibrations is known as Seismograph.

Magnitude scale

• Richter scale is used to measure the Magnitude of the earthquake
• The energy released during a quake is expressed in absolute numbers of 0-10.

Intensity scale

• The mercalli scale is used to measure the intensity of an earthquake
• It measures the visible damage caused due to the quake.
• It is expressed in the range of 1-12.

Question 29

Volcanoes

Answer 29

1. A volcano is a vent or fissure in Earth’s crust through which lava, ash, rocks, and gases erupt.
2. An active volcano is a volcano that has erupted in the recent past.
3. The mantle contains a weaker zone known as asthenosphere.
4. Magma is the material present in the asthenosphere.
5. Material that flows to or reaches the ground comprises lava flows, volcanic bombs, pyroclastic debris, dust, ash and gases. The gases maybe sulphur compounds, nitrogen compounds, and trace amounts of argon, hydrogen and chlorine.

Question 30

Major types of volcanoes

Answer 30

Volcanoes are classified on the basis of nature of eruption and the form developed at the surface.

1. Shield Volcanoes
2. Composite Volcanoes
3. Caldera
4. Flood Basalt Provinces
5. Mid-Ocean Ridge Volcanoes

Question 31

Shield Volcanoes

Answer 31

1. The Shield volcanoes are the largest of all the volcanoes on the earth, which are not steep.
2. These volcanoes are mostly made up of basalt.
3. They become explosive if in some way water gets into the vent, otherwise, they are characterized by low-explosivity.
4. The lava that is moving upwards does so in a fountain-form and emanates the cone at the vent’s top and then develops into cinder cone.
5. Eg: Hawaiian shield volcanoes

Question 32

Composite Volcanoes

Answer 32

1. Composite Volcanoes are characterized by outbreaks of cooler and more viscous lavas than basalt.
2. They are constructed from numerous explosive eruptions.
3. Large quantities of pyroclastic material and ashes find their way to the ground along with lava.
4. This material gathers near the vent openings resulting in the creation of layers.
5. Mayon Volcano in the Philippines, Mount Fuji in Japan, and Mount Rainier in Washington are the major composite volcanoes in the world.
6. The major composite volcano chains are Pacific Rim which known as the “Rim of Fire”.

Question 33

Caldera

Answer 33

1. Calderas are known as the most explosive volcanoes of Earth.
2. They are generally explosive in nature.
3. When they erupt, they incline to collapse on themselves rather than constructing any structure.
4. The collapsed depressions are known as calderas.

Question 34

Flood Basalt Provinces

Answer 34

1. Flood Basalt Province volcanoes discharge highly fluid lava that flows for long distances.
2. Many parts of the world are covered by thick basalt lava flows.

Question 35

Mid-Ocean Ridge Volcanoes

Answer 35

1. These volcanoes are found in the oceanic areas.
2. There exists a system of mid-ocean ridges stretching for over 70000 km all through the ocean basins.
3. The central region of this ridge gets frequent eruptions.

Question 36

Volcanic landforms

Answer 36

Volcanic eruptions result in the formation of landforms as given below:

1. Intrusive Forms
2. Batholiths
3. Lopolith
4. Phacolith
5. Sills
6. Dykes

Question 37

Intrusive Forms

Answer 37

1. The lava that is discharged during volcanic eruptions on cooling develops into igneous rocks.
2. The cooling may take place either on arriving on the surface or also while the lava is still in the crustal portion.
3. According to the location of the cooling of the lava, igneous rocks are categorized as plutonic rocks and volcanic rocks.
4. The lava that cools inside the crustal portions takes diverse forms. These forms are called intrusive forms.

Some of the forms are shown in Figure given below

Question 38

Batholiths

Answer 38

1. Batholiths are the cooled portion of magma chambers.
2. It is a large body of magmatic material that cools in the deeper depth of the crust moulds in the form of large domes.
3. They appear on the surface only after the denudation processes eliminate the overlying materials.
4. These are granitic bodies.

Question 39

Laccoliths

Answer 39

1. These are large dome-shaped intrusive bodies with a level base and linked by a pipe-like channel from below.
2. It bears a similarity to the surface volcanic domes of the composite volcano, only these are located at deeper depths.
3. It can be considered as the localized source of lava
4. The Karnataka plateau is patterned with dome hills of granite rocks.

Question 40

Lopolith

Answer 40

1. When the lava moves upwards, a part of the same tends to move in a horizontal direction wherever it finds a weak plane.
2. It can get rested in various forms. If it develops into a saucer shape, concave to the sky body, it is called lopolith.

Question 41

Phacolith

Answer 41

1. It is a wavy mass of intrusive rocks found at the base of synclines or at the top ofthe anticline in the folded igneous country.
2. These wavy materials have a definite outlet to source beneath in the form of magma cavities.

Question 42

Sills

Answer 42

1. The near horizontal bodies of the intrusive igneous rocks are called sill
2. The thick horizontal deposits are called sills whereas the thinner ones are called sheets.

Question 43

Dykes

Answer 43

1. Dykes are the most commonly found intrusive forms in the western Maharashtra area.
2. When the lava makes its channel through cracks and the fissures, it solidifies almost perpendicular to the ground.
3. This gets cooled in the same position to grow a wall-like structure. Such structures are known as dykes.
4. These are regarded as the feeders for the eruptions that led to the development of the Deccan traps.

Question 44

The earth is surrounded by a blanket of air known as atmosphere. All living beings on this earth depend on this atmosphere for their survival. It provides us the air we breathe and protects us from the harmful sun’s rays.

Composition of the Atmosphere

Answer 44

1. Nitrogen-is the most plentiful gas in the air.
2. Plants need nitrogen for their survival.
3. Oxygen- is the second most abundant gas in the air.
4. Humans and animals take oxygen from the air as they inhale.
5. Carbon dioxide- is another most important gas.
6. Green plants use carbon dioxide to make their food and release oxygen.
7. Argon

Question 45

Structure of the Atmosphere

Answer 45

Our atmosphere is divided into five layers starting from the earth’s surface.

1. Troposphere-the most important layer of the atmosphere. Its average height is 13 km. The air we inhale exists here. Most weather phenomena like rainfall, hailstorm, etc. occur in this layer.
2. Stratosphere- just above the troposphere lies the stratosphere. It extends up to a height of 50 km. Being free from associated weather phenomenon, this layer is most ideal for flying aeroplanes. Contains ozone.
3. Mesosphere-: This is the next & third layer of the atmosphere. It lies above the stratosphere. It extends up to the height of 80 km.
4. Thermosphere -In thermosphere temperature rises very rapidly with increasing height. Ionosphere is a part of this sphere. It extends between80-400 km. This layer helps in radio communications.
5. Exosphere-The last & upper most layer of the atmosphere is known as exosphere.

Question 46

Weather and Climate

Answer 46

1. Weather is day to day condition of the atmosphere.
2. The average weather condition of a place for a longer period of time represents the climate of a place.
3. Temperature-The degree of hotness and coldness of the air (body) is known as temperature.
4. Air Pressure-is defined as the pressure exerted by the weight of air on the earth’s surface.
5. Wind-The movement of air from high pressure area to low pressure areas is called wind.
6. Winds can be broadly divided into three types

• Permanent winds – The trade winds, easterlies and westerlies are the permanent winds. They blow throughout the year constantly in a particular direction.
• Seasonal winds – These winds change their direction in different seasons- example monsoon winds in India.
• Local winds – These winds blow only during a certain period of the day or year in a small area. For example, land breeze and sea breeze. – Ex-hot and dry local wind of northern plains of India is called loo.

Question 47

Our Changing Earth

Answer 47

Question 48

Lithospheric Plates

Answer 48

1. Lithospheric Plates: The lithosphere broken into a number of plates is known as the Lithospheric plates.
2. These plates move around very slowly – just a few millimetres each year.
3. This is because of the movement of the molten magma inside the earth.
4. The movement of these plates causes changes on the surface of the earth.
5. The earth movements are divided based on the forces that cause them on the basis of the forces which cause them

• Endogenic forces: The forces which act in the interior of the earth.
• Endogenic forces sometimes produce abrupt movements due to which earthquakes and volcanoes occur and cause mass destruction over the surface of the earth and at the other times produce slow movements.
• Exogenic forces: The exogenic forces work on the surface of the earth.

1. Volcano: It is an opening or a vent in the earth’s crust through which molten material erupts.
2. Earthquakes: Lithospheric plates move, the surface of the earth vibrates. The vibrations can travel all round the earth. These vibrations are called earthquakes.
3. Focus: The place in the crust where the movement starts is called the focus.
4. Epicentre: The place on the surface above the focus is called the epicentre.

Question 49

Major Land Forms

Answer 49

1. The landscape is being continuously worn away by two processes,

• Weathering: the breaking up of the rocks on the earth’s surface is called weathering
• Erosion: the wearing away of the landscape by different agents like water, wind and ice is called erosion

1. Work of a River: When the river tumbles at steep angle over very hard rocks or down a steep valley side it forms a waterfall.
2. Work of Sea Waves: The coastal ladnforms are formed due to the erosion and deposition of the sea waves.
3. Work of Ice: Glaciers are “rivers” of ice which too erode the landscape by bulldozing soil and stones to expose the solid rock below.
4. Work of wind: An active agent of erosion and deposition in the deserts is wind. In deserts you can see rocks in the shape of a mushroom, commonly called mushroom rocks.

Question 50

Inside Our Earth

• The earth, is a dynamic planet.
• It is constantly undergoing changes inside and outside.

Interior of the Earth

Answer 50

1. The earth is made up of several concentric layers with one inside another.
2. Crust-
3. The uppermost layer over the earth’s surface.
4. It is the thinnest of all the layers.
5. It is about 35 km. on the continental masses and only 5 km. on the ocean floors.
6. The main mineral constituents of the continental mass are silica and alumina. It is thus called si-al (si-silica and al-alumina)
7. The oceanic crust mainly consists of silica and magnesium; it is therefore called sima (si-silica and ma-magnesium)
8. Mantle-
9. Just beneath the crust is the mantle which extends up to a depth of 2900 km.
10. Core-
11. The innermost layer is the core with a radius of about 3500 km.
12. It is mainly made up of nickel and iron and is called nife (ni – nickel and fe – ferrous i.e. iron).
13. The central core has very high temperature and pressure.

Question 51

Rocks and Minerals

Answer 51

1. The earth’s crust is made up of various types of rocks.
2. Rock- Any natural mass of mineral matter that makes up the earth’s crust.
3. There are three major types of rocks-
4. Igneous rocks-when the molten magma cools; it solidifies to become igneous rock.
5. Sedimentary rocks- igneous rocks are broken down into small particles that are transported and deposited to form sedimentary rocks.
6. Metamorphic rocks- When the igneous and sedimentary rocks are subjected to heat and pressure they change into metamorphic rocks.
7. Rocks are made up of different minerals.
8. Minerals- are naturally occurring substances which have certain physical properties and definite chemical composition.
9. Minerals are very important to humankind. Some are used as fuels. For example, coal, natural gas and petroleum. They are also used in industries – iron, aluminium, gold, uranium, etc, in medicine, in fertilisers, etc.

Question 52

Environment

Answer 52

1. The place, people, things and nature that surround any living organism is called environment.
2. It is a combination of natural and human-made phenomena.
3. The natural environment refers to both biotic and abiotic conditions existing on the earth.

• Biotic- The world of living organisms. E.g. plants and animals.
• Abiotic- The world of non-living elements. E.g. land.

Question 53

Natural Environment

Answer 53

1. Lithosphere
2. Hydrosphere
3. Atmosphere
4. Biosphere

Question 54

Lithosphere

Answer 54

1. It is the solid crust or the hard top layer of the earth. It is made up of rocks and minerals and covered by a thin layer of soil.
2. Lithosphere is the domain that provides us forests, grasslands for grazing, land for agriculture and human settlements. It is also a source of mineral wealth.

Question 55

Hydrosphere

Answer 55

1. The domain of water is referred to as hydrosphere
2. It comprises various sources of water and different types of water bodies like rivers, lakes, seas, oceans, etc.

Question 56

Atmosphere

Answer 56

1. It is the thin layer of air that surrounds the earth.
2. The gravitational force of the earth holds the atmosphere around it.
3. It protects us from the harmful rays and scorching heat of the sun.
4. It consists of a number of gases, dust and water vapour. The changes in the atmosphere produce changes in the weather and climate.

Question 57

Biosphere

Answer 57

1. Plant and animal kingdom together make biosphere.
2. It is a narrow zone of the earth where land, water and air interact with each other to support life.

Question 58

What is ecosystem?

Answer 58

• All plants, animals and human beings depend on their immediate surroundings. This relation between the living organisms, as well as the relation between the organisms and their surroundings, forms an ecosystem.

Question 59

OUR COUNTRY – INDIA

India’s Geographical Expanse

Answer 59

India is a country of massive geographical area.

It is bound by-

• The lofty Himalayas in the North;
• The Arabian Sea in the West;
• The Bay of Bengal in the East; and
• The Indian Ocean in the South

India has an area of about 3, 28 million sq. km.

• The north-south extent from Kashmir to Kanyakumari measures about 3,200 km.
• The east-west extent from Arunachal Pradesh to Kucchi measures about 2,900 km.

Question 60

India’s Location Setting

Answer 60

India is located in the Northern Hemisphere

The Tropic of Cancer (23°30′ N) passes almost halfway through the country.

Latitude and Longitude of India

Latitude: 8°4′ N and 37°6′ N, from south to north.

Longitudes: 68°7′ E and 97°25′ E, from west to east.

Question 61

India’s Neighbours

Answer 61

1. There are seven countries that share land boundaries with India.
2. Sri Lanka is separated from India by the Palk Strait.

Question 62

Political and Administrative Divisions

Answer 62

India is a vast country. For administrative purposes, the country is divided into 29 states and 7 Union Territories. Telangana became the 29th state of India on 2 June 2014.

Question 63

Our Country India Physical Features

Physical Divisions

Answer 63

1. The Himalayan mountains- They are divided into three main parallel ranges. The northernmost is the Great Himalaya or Himadri. The world’s highest peaks are located in this range. Middle Himalaya or Himachal lies to the south of Himadri. The Shiwalik is the southernmost range.
2. Northern Indian plains- They lie to the south of the Himalayas. They are generally level and flat.
3. Great Indian desert- They lie In the western part of India. It is a dry, hot and sandy stretch of land. It has very little vegetation.
4. Peninsular plateau- It lies to the south of northern plains. It is triangular in shape. The relief is highly uneven. This is a region with numerous hill ranges and valleys.
5. The Vindhyas and the Satpuras are the important ranges. The rivers Narmada and Tapi flow through these ranges. These are west-flowing rivers that drain into the Arabian Sea. In the west, the Western Ghats or Sahyadris border the plateau and the Eastern Ghats provide the eastern boundary.
6. Coastal plains – They lie to the West of the Western Ghats and the East of Eastern Ghats. Western coastal plains are very narrow. The eastern Coastal plains are much broader.
7. Islands -Two groups of islands also form part of India. Lakshadweep Islands are located in the Arabian Sea. These are coral islands located off the coast of Kerala. The Andaman and the Nicobar Islands lie to the southeast of the Indian mainland in the Bay of Bengal.

Question 64

India : Climate, Vegetation And Wildlife

Weather

Answer 64

It is about the day to day changes in the atmosphere. It includes changes in temperature, rainfall and sunshine etc.

Question 65

Climate

Answer 65

1. It is about the average weather condition, which have been measured over many years.
2. The climate of a place is affected by its,

• Location
• Altitude
• Distance from the sea
• Relief

The major seasons recognized in India:

1. Cold Weather Season (Winter) – (December to February) The sun rays do not fall directly in the region. As a result the temperatures are quite low in northern India.
2. Hot Weather Season (Summer)- (March to May) In the hot weather season sun rays more or less directly fall in this region. Temperature becomes very high.
3. Southwest Monsoon Season (Rainy)- (June to September) This season is marked by the onset and advance of monsoon. The winds blow from Arabian Sea and Bay of Bengal towards the land. They carry moisture with them. When these winds strike the mountain barriers, rainfall occurs.
4. Season of Retreating Monsoon (Autumn)- (October and November) Winds move back from the mainland to the Bay of Bengal. This is the season of the retreating monsoons. The southern parts of India, particularly Tamil Nadu and Andhra Pradesh receive rainfall in this season.

Question 66

Natural Vegetation

Answer 66

The grasses, shrubs and trees, which grow on their own without interference or help from human beings are called natural vegetation.

1. Tropical Rain Forest
2. Tropical Deciduous Forests
3. Thorny Bushes
4. Mountain Vegetation
5. Mangrove Forests

Question 67

India’s Wild Life

Answer 67

1. The tiger is our national animal. It is found in various parts of the country. Gir forest in Gujarat is the home of Asiatic lions. Elephants and one-horned rhinoceroses roam in the forests of Assam. Elephants are also found in Kerala and Karnataka. Camels and wild asses are found in the Great Indian desert and the Rann of Kuchchh respectively. Wild goats, snow leopards, bears, etc. are found in the Himalayan region. Besides these, many other animals are found in our country such as monkey, wolf, jackal, nilgai, cheetah, etc.
2. India is equally rich in bird life. The peacock is our national bird. Other common birds are parrots, pigeons, mynah, geese, bulbul, and ducks.
3. There are several hundreds of species of snakes found in India. Cobras and kraits are important among them.
4. In order to protect them many national parks, sanctuaries and biosphere reserves have been set up. The Government has also started Project Tiger and Project Elephant to protect these animals.

Question 68

Major Landforms of the Earth

Answer 68

The surface of the earth is uneven, some parts may be rugged and some flat. The earth has an immeasurable variety of landforms.

These landforms are a result of two processes and they are:

1. Internal process- The Internal Process leads to the upliftment and sinking of the earth’s surface.
2. External process- It is the continuous wearing down and rebuilding of the land surface and includes two processes namely:

• Erosion– It is the wearing away of the earth’s surface.
• Deposition– It is the rebuilding of a lowered surface (occurred due to erosion).

The erosion and deposition processes are carried out by running water, ice and wind.

Landforms can be grouped based on the elevation and slope and they are:

1. Mountains
2. Plateaus
3. Plains

Question 69

MOUNTAINS

Answer 69

1. Any natural elevation of the earth surface is called a Mountain.
2. Range- Mountains arranged in a line.
3. Glaciers – Glaciers are permanently frozen rivers of ice in mountains.

There are three types of mountains and they are:

1. Fold Mountains

• They are rugged relief and high conical peaks.
• g. Himalayan Mountains and the Alps (Young fold mountains)
• The Aravali range in India (oldest fold mountain system in the world)
• The Appalachians in North America and the Ural mountains in Russia (very old fold mountains)

1. Block Mountains

• Created when large mass of land are broken and displaced vertically.
• The Rhine valley and the Vosges mountain in Europe

1. Volcanic Mountains

• Formed due to volcanic activity.
• Mt. Kilimanjaro in Africa and Mt. Fujiyama in Japan.

How the Mountains are useful?

• Mountains are very useful in various ways.
• They are storehouse of water and many rivers have their basis in the glaciers in the mountain.
• Reservoirs are made and water is harnessed for the use of people.
• Water from the mountains is also used for irrigation and generation of hydro-electricity.
• Mountains have a rich variety of flora and fauna.
• The forests provide fuel, fodder, shelter and other products like gum, raisins, etc.
• Mountains also provide a tranquil site for tourists.

Question 70

PLATEAUS

Answer 70

• A plateau is an elevated flat land.
• It is a flat-topped table land standing above the surrounding area.
• e.g. The Deccan plateau in India is one of the oldest plateaus.
• The Western plateau of Australia, the East African Plateau in Kenya (The Tanzania and Uganda), the Tibet plateau (the highest plateau in the world) etc.

How the Plateaus are useful?

• Plateaus are very useful as they are rich in mineral deposits.
• E.g. African plateau is famous for gold and diamond mining
• Chhotanagpur plateau in India is a huge reserves of iron, coal and manganese

Question 71

PLAINS

Answer 71

1. Plains are large stretches of flat land.
2. Generally, not more than 200 metres above mean sea level.
3. Generally, plains are very fertile; hence these plains are very thickly-populated regions of the world.

• E.g. largest plains made by the rivers are found in Asia and North America
• Large plains in Asia are formed by the Ganga and the Brahmaputra in India and the Yangtze in China.

How the Plains are useful?

1. Plains are the most useful areas for human habitation.
2. Building houses, construction of transport network, as well as for cultivation is easy.
3. In India, the Indo-Gangetic plains are the most densely populated regions.

Question 72

Major Domains of The Earth

Answer 72

The earth’s surface is a complex zone in which the three major components of the environment meet, overlap and interact.

The Four Domains of the Earth

1. Lithosphere: The solid portion of the earth
2. Atmosphere: The gaseous layers that surround the earth
3. Hydrosphere: Water covers a very big area of the earth’s surface and this area is called the Hydrosphere
4. Biosphere: It is the narrow zone where land, water and air together are found.

Question 73

Lithosphere

Answer 73

• The solid portion of the earth is called the Lithosphere.
• It comprises the rocks of the earth’s crust and the thin layers of soil that contain nutrient elements which sustain organisms.

There are two main divisions of the earth’s surface:

1. Continents- the large landmasses.
2. Ocean basins- the huge water bodies.

Mt. Everest is the highest mountain peak measuring 8,848 metres above the sea level. The greatest depth of 11,022 metres is recorded at Mariana Trench in the Pacific Ocean.

Question 74

Continents

Answer 74

There are seven major continents and these are separated by large water bodies.

1. Asia
2. Europe
3. Africa
4. North America
5. South America
6. Australia
7. Antarctica

Question 75

Asia

Answer 75

1. Asia is the largest continent covering one-third of the total land area of the earth.
2. The continent lies in the Eastern Hemisphere.
3. The Tropic of Cancer passes through Asia.
4. The Ural mountains on the west separates from Europe.

Question 76

Europe

Answer 76

1. Europe is much smaller than Asia lying to the west of Asia.
2. The Arctic Circle passes through it.
3. Its three sides are bound by water bodies.

Question 77

Africa

Answer 77

1. Africa is the second largest continent after Asia.
2. A large part of Africa lies in the Northern Hemisphere.
3. Africa is the only continent through which the Tropic of Cancer, the Equator and the Tropic of Capricorn pass.

The Sahara Desert, the world’s largest hot desert, is located in Africa. The continent is bound on all sides by oceans and seas. The world’s longest river the Nile, flows through this continent.

Question 78

North America

Answer 78

1. North America is the third largest continent of the world.
2. The continent lies completely in the Northern and Western Hemisphere.
3. The Isthmus of Panama a narrow strip links North America and South America.
4. This continent is surrounded by three oceans and they are the Atlantic Ocean, the Pacific Ocean, and the Arctic Ocean.

Question 79

South America

Answer 79

1. South America lies mostly in the Southern Hemisphere.
2. It is surrounded by two oceans; the Pacific Ocean on the west and the Atlantic Ocean on the east and north.

The world’s longest mountain range, The Andes and the world’s largest river, the Amazon are in South America.

Question 80

Australia

Answer 80

1. Australia is the smallest continent that lies entirely in the Southern Hemisphere.
2. It is surrounded on all sides by the oceans and seas.
3. It is called an island continent.

Question 81

Antarctica

Answer 81

• Antarctica is a huge continent and lies completely in the Southern Hemisphere.
• The South Pole lies in the South Polar Region almost at the centre of this continent and is permanently covered with thick ice sheets.

Various countries have their research stations here. India also has its research stations here, namely Maitri and Dakshin Gangotri.

Question 82

Hydrosphere

Answer 82

1. The earth is called the blue planet.
2. More than 71 per cent of the earth is covered with water and 29 per cent is with land. Hydrosphere consists of water in all its forms.
3. More than 97% of the Earth’s water is found in the oceans and is too salty for human use.
4. Hydrosphere consists of water in all its forms like running water in oceans and rivers and in lakes, ice in glaciers, underground water and the water vapour in atmosphere.
5. 97% of the Earth’s water is found in the oceans and is too salty, the rest of the water is in the form of icesheets and glaciers or under the ground and a very
6. small percentage is available as fresh water for human use

Question 83

Oceans

Answer 83

• The three chief movements of ocean waters are the waves, the tides and the ocean currents.
• Oceans are the major part of hydrosphere and they are all interconnected.
• The five major oceans in order of their size are
  
  1. The Pacific Ocean: It is almost circular in shape. Asia, Australia, North and South Americas surround it.
  2. The Atlantic Ocean: It is the second largest Ocean in the world. It is ‘S’ shaped. It is flanked by the North and South Americas on the western side, and Europe and Africa on the eastern side.
  3. The Indian Ocean: It is the only ocean named after a country, that is, India. The shape of ocean is almost triangular. In the north, it is bound by Asia, in the west by Africa and in the east by Australia.
  4. The Southern Ocean: It surrounds the continent of Antarctica
  5. The Arctic Ocean: It is located within the Arctic Circle and surrounds the North Pole. The Berring strait a narrow stretch of shallow water connects it with the Pacific Ocean.

Question 84

Atmosphere

Answer 84

The earth is surrounded by a layer of gas called the atmosphere.

• The atmosphere extends up to a height of about 1,600 kilometres.
• The atmosphere is divided into five layers based on composition, temperature and other properties and they are:

1. the troposphere
2. the stratosphere
3. the mesosphere
4. the thermosphere
5. the exosphere

• A bout 99 per cent of clean and dry air in the atmosphere is composed mainly of nitrogen and oxygen. Nitrogen 78 per cent, oxygen 21 per cent and other gases like carbondioxide, argon and others comprise 1 per cent by volume.

Question 85

Biosphere – The Domain of Life

Answer 85

1. The biosphere is the narrow zone of contact between the land, water and air.
2. It is the zone where life exists that makes this planet unique.
3. The organisms in the biosphere are commonly divided into:

• the plant kingdom
• the animal kingdom

1. The three domains of the earth interact with each other and affect each other in some way or the other.

Question 86

MOTIONS OF THE EARTHLatitudes and Longitudes

Answer 86

Rotation

• Rotation is the movement of the earth on its axis

Revolution

• Revolution is the movement of the earth around the sun in a fixed path or orbit

Orbital Plane

• Orbital plane is the plane formed by the orbit.

The axis of the earth

• The axis of the earth is an imaginary line that makes an angle of 66½° with its orbital plane.

Question 87

Circle of Illumination

Answer 87

1. The circle of illumination is the circle that divides the day from night on the globe.
2. It takes 365¼ days (one year) for earth to revolve around the sun.
3. Six hours saved every year are added to make one day (24 hours) over a span of four years. This surplus day is added to the month of February. Thus every fourth year we have leap year with 366 days.
4. Earth goes around the sun in an elliptical orbit. Note that throughout its orbit, the earth is inclined in the same direction.

Question 88

Seasons

Answer 88

1. A year is usually divided into summer, winter, spring and autumn seasons.
2. Seasons change due to the change in the position of the earth around the sun.
3. Summer Solstice: The longest day and the shortest night. It occurs on 21st June in northern hemisphere

On 21st June, the Northern Hemisphere is tilted towards the sun. The rays of the sun fall directly on the Tropic of Cancer. Therefore, these areas experience more heat. The areas near the poles receive less heat as the rays of the sun are slanting. The North Pole is inclined towards the sun and the places beyond the Arctic Circle experience continuous daylight for about 6 months.

Question 89

Winter Solstice

Answer 89

The nights are longer than the days. It occurs On 22nd December.

( On 22nd December, the Tropic of Capricorn receives direct rays of the sun as the South Pole tilts towards it. As the sun’s rays fall vertically at the Tropic of Capricorn (23½° S), a larger portion of the Southern Hemisphere gets light)

Question 90

Equinox

Answer 90

The whole earth experiences equal days and equal nights. It occurs on 21st March and September 23rd.

(On 21st March and September 23rd, direct rays of the sun fall on the equator. At this position, neither of the poles is tilted towards the sun)

Question 91

Maps

Answer 91

Map is a representation or a drawing of the earth’s surface or a part of it on a flat surface according to a scale.

Question 92

Types of Maps

Answer 92

1. Physical or Relief Maps
   * Maps showing natural features of the earth such as mountains, plateaus, plains, rivers, oceans etc. are known as physical or relief maps.
2. Political Maps
   * Maps showing cities, towns, villages, states, and different countries of the world with their boundaries are called political maps.
3. Thematic Maps
   * Maps that focus on specific information like road maps, rainfall maps, distribution of forests, industries etc. are called thematic maps.
4. Sketch
   * It is a drawing mainly based on memory and spot observation and not to scale
5. Plan

• It is a drawing of a small area on a large scale.
• A large-scale map gives a lot of information.

Question 93

Components of Maps

Answer 93

1. Distance
   * Maps are drawings, which reduce the entire world or a part of it to fit on a sheet of paper. A scale is being used to do this accurately. A scale is a ratio between the actual distance on the ground and the distance shown on the map
2. Direction

• There are 4 cardinal points namely-North, South, East, West.
• Other four intermediate directions are north-east (NE), southeast(SE), south-west (SW) and north-west (NW)
• It is possible to locate any place more accurately with the help of these intermediate directions.

1. Symbols

• Different features such as buildings, roads, bridges, trees, railway lines or a well. So, they are shown by using certain letters, shades, colours, pictures and lines on the maps. These symbols give a lot of information in a limited space.
• With the use of these symbols, maps can be drawn easily and are simple to read.

Question 94

Latitudes

Answer 94

1. Equator

• Equator is an imaginary line running on the globe that divides it into two equal parts.
• Northern half of the earth is known as the Northern Hemisphere and Southern half is known as the Southern Hemisphere.

1. Parallels of latitudes

• Parallels of latitudes are parallel circles from the equator up to the poles.
• They are measured in degrees.

The equator represents the zero degrees latitude. Its distance from the equator to either of the poles is one-fourth of a circle round the earth, it will measure ¼th of 360 degrees, i.e. 90°. Thus, 90 degrees north latitude marks the North Pole and 90 degrees south latitude marks the South Pole.

1. Important Parallels of Latitudes

• Tropic of Cancer (23½° N) in the Northern Hemisphere
• Tropic of Capricorn (23½° S) in the Southern Hemisphere
• Arctic Circle at 66½° north of the equator
• Antarctic Circle at 66½° south of the equator

Question 95

Heat Zones of the Earth

Answer 95

1. Torrid Zone
   * The mid-day sun is exactly overhead at least once a year on all latitudes in between the Tropic of Cancer and the Tropic of Capricorn. It therefore, receives the maximum heat.
2. Temperate Zones
   * The mid-day sun never shines overhead on any latitude beyond the Tropic of Cancer and the Tropic of Capricorn. The angle of the sun’s rays goes on decreasing towards the poles. and the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere, They have moderate temperatures
3. Frigid Zones
   * Areas lying between the Arctic Circle and the North Pole in the Northern Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere, are very cold. It is because here the sun does not rise much above the horizon.

Question 96

Longitudes

Answer 96

1. Prime Meridian

• The meridian which passed through Greenwich, where the British Royal Observatory is located. This meridian is considered as the Prime Meridian.
• Its value is 0° longitude and from it we count 180° eastward as well as 180° westward. The Prime Meridian and 180° meridian divide the earth into two equal halves, the Eastern Hemisphere and the Western Hemisphere

1. Longitude and Time

• The best means of measuring time is by the movement of the earth, the moon and the planets. The sun regularly rises and sets every day.
• When the Prime Meridian of Greenwich has the sun at the highest point in the sky, all the places along this meridian will have mid-day or noon.
• As the earth rotates from west to east, those places east of Greenwich will be ahead of Greenwich time and those to the west will be behind it.
• It can be calculated this way- The earth rotates 360° in about 24 hours, which means 15° an hour or 1° in four minutes. Thus, when it is 12 noon at Greenwich, the time at 15° east of Greenwich will be 15 × 4 = 60 minutes, i.e., 1 hour ahead of Greenwich time, But at 15° west of Greenwich, the time will be behind Greenwich time by one hour

Question 97

Why do we have Standard Time?

Answer 97

1. The local time of places which are on different meridians are bound to differ.
2. In India, for instance, there will be a difference of about 1 hour and 45 minutes in the local times of Dwarka in Gujarat and Dibrugarh in Assam.
3. In India, the longitude of 82½° E (82° 30’E) is treated as the standard meridian. The local time at this meridian is taken as the standard time for the whole country. It is known as the Indian Standard Time (IST).

Question 98

Celestial Bodies

Answer 98

1. Celestial bodies are objects like Sun, moon, stars and others that shine in the night sky.
2. Some celestial bodies are very big and are made up of gases and heat. They have their own heat and light which is emitted in large amounts. These celestial bodies are called stars and our Sun is a star.
3. The sun, the moon and all those shining objects in the night sky are called celestial bodies.

Question 99

Constellations

Answer 99

1. Different groups of stars form various patterns and they are called constellations. Saptarshi is an example of constellations.
2. In ancient times, with the help of stars directions were determined during night time. The North Star indicates the north direction (Pole Star) and it remains in the same position in the sky.
3. Celestial bodies that do not have their own heat and light and lit by the light of the stars are called planets.

Question 100

Solar System

Answer 100

The solar system is made up of the Sun, eight planets, satellites and other celestial bodies.

Question 101

The Sun

Answer 101

1. The sun is in the centre of the solar system.
2. It is huge and made up of extremely hot gases.
3. It provides the pulling force that binds the solar system.

Question 102

Planets

Answer 102

• There are eight planets in our solar system.
• In order of their distance from the sun, they are:

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus and
8. Neptune

Question 103

Inner Planets

Answer 103

1. These planets are very close to the sun.
2. They are made up of rocks.
3. Inner Planets are:

• MERCURY- One orbit around sun – 88 days, One spin on axis – 59 days.
• VENUS – One orbit around sun – 255 days. One spin on axis – 243 days
• EARTH – One orbit around sun – 365 days. One spin on axis – 1 day Number of moons – 1
• MARS – One orbit around sun – 687 days One spin on axis – 1 day, number of moons – 02

Question 104

Outer Planets

Answer 104

• Very-very far from the sun and are huge planets made up of gases and liquids

1. JUPITER – One orbit around sun – 11 years, 11 months about 12 years. One spin on axis – 9 hours, 56 minutes, number of moons – 16
2. SATURN – One orbit around sun – 29 years, 5 months. One spin on axis – 10 hours 40 minutes, number of moons – about 18.
3. URANUS – One orbit around sun – 84 years. One spin around axis – 17 hours 14 minutes, number of moons – about 17.
4. NEPTUNE – One orbit around sun – 164 years. One spin on axis-16 hours 7 minutes, number of moons – 8

Question 105

Asteroids

Answer 105

1. Asteroids are numerous tiny bodies which also move around the Sun apart from the stars, planets and satellites.
2. They are found between the orbits of Mars and Jupiter.

Question 106

Meteoroids

Answer 106

• Meteoroids are small pieces of rocks which move around the sun.