6.Chapter5.Geography.Realms of the Earth

Chapter-5.Geography. 
Chapter- Realms of the Earth

Keywords
Interdependent : depending on one another for survival or existence.
Isthmus : it is narrow  strip of land that  joins two  large  areas  of land.It is
always  surrounded  by sea on either side.
Ozone layer : the layer present in stratosphere around  15 to 30 km above the surface of earth.This layer protects earth from harmful ultraviolet  radiation of the sun
Sea level : the level pf the surface of the sea with respect to the land. It is taken as a mean level between high and low tide, and used as a standard base for measuring heights and depths.

Internal questions : -
Q.1. List the four realms of the Earth.
Ans -The Earth can be divided into four realms: -
(1). Lithosphere
(2). Hydrosphere
(3). Atmosphere
(4). Biosphere
Q.2.What is the meaning of the word “Litmos”?
Ans- “Litmos” is a Greek word which means “stone” or “rock”.
Q.3.Define Lithosphere.
Ans -The upper surface of the earth, consisting of a thin layer of rock material, is called Lithosphere.
4.What is called a Continent ?
Ans -The large continuous masses of land above the sea level is called a continent.
Q.5.Name the all seven continents of the world.
Ans-The seven of the worlds are: -
(1). Asia
(2). Africa
(3). Europe
(4). North America 
(5). South America 
(6). Australia
(7). Antarctica
Q.6.Which continent is known as Dark continent and Why?
Ans - Africa is known as Dark continent because people of other parts did not know much about this continent.
Q.7.What is the other name of Australia?
Ans -The other name of Australia is Oceania.
Q.8.Write the first two names of permanent research bases of India in Antarctica?
Ans-The first two permanent research bases of India in Antarctica are: -
(a). Dakshin Gangotri’
(b). Maitra
Q.9.Name the highest mountain peak in the world and write its height.
Ans - Mount Everest is the highest mountain peak in the world. Its height is about 8850 metres above the sea level

Something to know :
A.Tick the correct option :
1.Which one of the following is an old mountain?
(b)The Aravalli range
2.How much surface of the earth is covered by oceans?
(b) 71%
3.The largest ocean of the world is -
(b)Pacific Ocean
4.Which continent is the most advanced and economically developed continent?
(d) Europe
5.Which one of the following gases has the largest volume in the atmosphere?
(a) Nitrogen

B. Fill in the blanks.
1. Biosphere is a narrow belt or zone of the earth where all forms of life exist.
2. An envelope of the air surrounding the earth is called Atmosphere.
3. Lithosphere   is the upper surface of the earth consisting of rocks.
4. A highly elevated land from the surrounding with very steep slopes is known as Mountain.
5. An upland with rugged surface is called Plateau.
C. Match the following :
1.It separates Europe and Asia - e.Ural mountain and Ural river
2. It joins North America with South America - c. Isthmus of Panama
3.The largest continent of the world - a. Asia
4.It helps in burning - b.Oxygen
5.Continent in southern hemisphere - d. Antarctica

D. Answer the following questions in brief.
Q.1.Name the four realms of the Earth.
Ans -The four realms of the earth are : Lithosphere,Hydrosphere, Atmosphere,Biosphere.
Q.2.Which four gases constitute only one per cent of the total volume of the atmosphere?
Ans - Carbon dioxide, Argon, Hydrogen, Helium constitute only one per cent of total volume of the atmosphere.
Q.3.Which continent is not inhabited by the people and why?
Ans- Antarctica is not inhabited by the people because there are very cold conditions.
Q.4.Why is earth known as a ‘unique planet’?
Ans-Earth is known as a unique planet because it consists of land, air and water as the major physical elements.
Q.5.Name the three major land forms of the land surface.
Ans-The three major land forms of the land surface are: - Mountains,Plateaus,Plains

E.Answer the following questions.
Q.1.What are Plains? Explain briefly the formation of plains.
Ans-Plains are relatively low-lying flat land.The slope of a plain is gentle and its average height is between 100 and 200 metres above the sea level. 
Most of the plain in the world have been formed by rivers.
The rivers carry away large volume of silt and sediments from the mountains and deposit them in low –lying areas to form Plains.
Q.2.Give a brief account of the plateaus of world.
Ans-The plateau of Tibet is also called Roof of the world, is the highest plateau in the world It's average height is about 5000 metres above the mean sea level.
Some are as the Deccan plateau in India, the Arabian plateau and the Brazil plateau.These are some of the large plateaus of the world.
Most of the plateaus are the storehouses of minerals,such as iron-ore gold, etc.
Q.3.Name the two main gases of the atmosphere. Write the significance of each.
Ans - Atmosphere contains several gases such as Nitrogen, Oxygen and Carbon Dioxide which are essential for life on the earth. 78% volume of nitrogen gas is present in the Atmosphere. 
Oxygen is about 21 % of the total volume. These two gases constitute about 99% of the total volume of the Atmospheric air. The amount of Carbon Dioxide, although very minutiae. 0.3% , is a very important part of the Atmosphere.
Q.4.What is meant by Hydrosphere?  Briefly explain the importance of Hydrosphere.
Ans-Hydrosphere refers to the layer of water on the surface of the earth and also in the air. Water covers about two-third of the total surface of the earth. Therefore, the earth, sometimes, is called the Watery planet. Water is present in the form of ice-sheets in the polar regions and no high mountains. Water also occurs on land in the form of lakes and rivers.
Q.5.How are human activities responsible for causing ecological imbalance?
Ans- It is the human being who interfaces and creates imbalance between the plants and animals. As the human population is increasing rapidly more space is required for different human activities, such as agriculture, industry and urbanisation.Man is destroying the forest carelessly and exploiting the resources. 
As a result of these activities, several problems have emerged before human beings, for example, soil erosion, floods, etc.
Beside these, pollution of air and water has increased beyond the point of control.

Map skill
Shade and label different continents as well as major oceans on an out-tine map of the world.