D. Answer the following questions in brief.
1. Name the four realms of the earth.
Answer:
The four realms of the earth are:
Lithosphere
Hydrosphere
Atmosphere
Biosphere
2. Which four gases constitute only one per cent of the total volume of the atmosphere?
Answer:
The four gases are:
Argon
Carbon dioxide
Neon
Helium
3. Which continent is not inhabited by people and why?
Answer:
Antarctica is not inhabited by people because it has extremely cold climate and remains covered with ice throughout the year.
4. Why is Earth known as a ‘unique planet’?
Answer:
Earth is known as a unique planet because it has air, water, suitable temperature and life-supporting conditions.
5. Name three major landforms on the land surface.
Answer:
The three major landforms are:
Mountains
Plateaus
Plains
E. Answer the following questions.
1. What are plains? Explain briefly the formation of plains.
Answer:
Plains are large, flat and low-lying areas of land.
Most plains are formed by the deposition of sediments brought by rivers. Over many years, layers of soil and sand get deposited, forming fertile plains.
2. Give a brief account of the plateaus of the world.
Answer:
Plateaus are elevated flat-topped areas. They are higher than plains but lower than mountains.
Some important plateaus of the world are:
Deccan Plateau (India)
Tibetan Plateau (Asia)
African Plateau
Plateaus are rich in minerals and are important for mining.
3. Name the two main gases of the atmosphere. Write the significance of each.
Answer:
The two main gases of the atmosphere are:
Nitrogen:
It helps in the growth of plants and dilutes oxygen to control rapid burning.
Oxygen:
It is essential for breathing and supports life on Earth.
4. What is meant by hydrosphere? Briefly explain its importance.
Answer:
Hydrosphere includes all the water bodies on Earth such as oceans, seas, rivers, lakes, glaciers and underground water.
Importance:
It supports life
Helps in climate control
Provides water for drinking, agriculture and industries
5. How are human activities responsible for causing ecological imbalance?
Answer:
Human activities like deforestation, pollution, excessive use of natural resources and industrial waste disturb the balance of nature, leading to ecological imbalance.
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