Class VI

Chapter-5   The Realms of Earth

Q1. Name the four realms of the earth?

A1. The earth can be divided into four realms:

   1.    The Lithosphere(Land)

   2.    The Hydrosphere(Water)

   3.    The Atmosphere(Air)

   4.    The Biosphere(Life)

Q2. Which four gases constitute only one percent of the total volume of the atmosphere?

A2. Gases that constitute only one percent of the total volume of the atmosphere are:

   1.    Argon

   2.    Hydrogen

   3.    Helium

   4.    Carbon Dioxide

Q3. Which continent is not inhabited by the people and why?

A3. 1. Antarctica is covered by with very thick sheets of ice and snow.

2. It is estimated that 3/4^th of the total mass of ice is found in Antarctica.

3. Due to very cold conditions the land is not inhabited by human beings.

Q4. Why is earth known as ‘unique planet’?

A4. 1. Our earth is known as a ‘unique planet’ because this is the only planet where life is known to exist.

2. It consists of land, air and water as the major physical elements.

3. The earth has all the favourable conditions which support life on the earth.

Q5. Define Relief or Landforms. Name three major landforms on the land surface.

A5.1. The difference in the height and slopes of the land surface is known as Landforms.

2. The major landforms are grouped as- mountains, plateaus, and plains.

E1. What are plains? Explain briefly the formation of plains.

A1.

1. A plain is a relatively low-lying flat land and its average height is between 100 and 200 metres above sea level.

2. Plains are densely populated as they have fertile soil, abundant supply of water and ideal climate.

3. Most of the plains in the world have been formed by rivers. eg. The Northern Plains of India has been formed by the Ganga river system.

4. The rivers carry away large volume of silt and sediments from the mountains and deposit them in low-lying areas to form plains.

5. Some of the  important plains are the Great China Plain, The Egyptian Plain and the Plain of Iraq.

E2. Give a brief account of the plateaus of the world.

A2. 

1. A plateau is an upland with rugged surface. It is like a tableland uplifted from its surroundings.

2. Its average height is 600 metres above the sea level.

3. The Plateau of Tibet also known as Roof of the World is the highest plateau of the World.

4. The Deccan Plateau in India, the Arabian Plateau and the Brazil Plateau are some of the large plateaus of the world.

5. Most of the plateaus are the storehouses of minerals, such as iron-ore, gold etc.

E3. Name the two main gases of the atmosphere. Write the significance of each.

A3. The two main gases of the atmosphere are Nitrogen and Oxygen.

Significance of Nitrogen

    1.    78% volume of gas in the atmosphere is Nitrogen.  

    2.    It is very essential for the biosphere to exist.

3. 3..    It is nitrogen that dilutes oxygen and prevents rapid burning at the earth’s surface.

Significance of Oxygen

    1.    Oxygen is 21% of the total volume.

    2.    It is very essential for the biosphere to exist.

    3.    It is essential for respiration and burning.

E4. What is meant by hydrosphere? Briefly explain the importance of hydrosphere.

A4.Hydrosphere refers to the layer of water on the surface of the earth, below the surface of the earth and also in the air.

Importance of Hydrosphere

   1.    The ocean facilitates countries and regions to trade with one another.

   

   2.    Goods can be moved in a very large quantity by ships and the water transport is cheaper than any other mode of transport.

   

   3.    The marine environment provides animal and plant life for food and trade in abundance.

   

   4.    Some of the valuable mineral resources are found in the ocean floor. Mineral oil, manganese nodules, gold, platinum, nickel, copper and cobalt.

   

  5.    Several countries are tapping mineral oils as a source of energy in a big way.

E5. How are human activities responsible for causing ecological imbalance?

A5..

1. Over population – rapid increase in the population has resulted in scarcity of resources

2. Deforestation- Cutting down of forest on large scale for fulfilment of human needs have resulted in imbalance in nature.

3. Besides these, pollution of air, Land and water and has increased beyond the point of control.

4. Excessive use of fossil fuels.

5. Urbanisation and Industrialisation have drastic effects on the nature.