Social Science STD 6 Chapter 10: Spheres of the Earth - Exercises

Social Science STD 6 Chapter 10: Spheres of the Earth - Exercises

1. Answer the following questions in 1-2 lines each:
  • 1. Which are the main spheres on the earth?
    The four main spheres on the Earth are the Lithosphere, Hydrosphere, Atmosphere, and Biosphere.
  • 2. What is meant by Lithosphere?
    The Lithosphere is the upper solid layer of the Earth's surface, which is made up of soil and solid matter. It is also known as the "rock sphere" or "solid-sphere".
  • 3. What is hydrosphere made up of?
    The Hydrosphere is made up of the water area of the Earth's surface, including oceans, seas, lakes, and rivers.
  • 4. Which are the main gases of atmosphere?
    The main gases of the atmosphere are nitrogen, oxygen, argon, and carbon-dioxide.
  • 5. Who is included in the biosphere?
    The Biosphere includes all forms of life, such as humans, animals, and plants.
2. Fill in the following blanks with the correct word:
  • 1. ........ sphere consists of mountains, plateaus and plains.
    Answer: Lithosphere
  • 2. Stretch of atmosphere is up to ........ K.m. above the earth surface.
    Answer: 850 to 1000
  • 3. ........ gas is present in maximum proportion in the environment.
    Answer: Nitrogen
3. Explain whether the following statements are true or false:
  • 1. Existence of oxygen in the environment is up to the height of 150 kilometres.
    Answer: False
  • 2. The oceans have become our water ways.
    Answer: True
  • 3. Biosphere consists of variety of life forms.
    Answer: True
  • 4. Biosphere develops on the earth surface because of water and air.
    Answer: True
  • 5. Ozone gas protects living being on earth surface from the ultraviolet rays of the sun.
    Answer: True
4. Write Short Note:
  • 1. Atmosphere
    The Atmosphere is a layer of gases that surrounds the Earth up to a height of approximately 850 to 1000 km. It is transparent, colorless, odorless, and tasteless. The atmosphere is composed of various gases like nitrogen, oxygen, argon, and carbon-dioxide, as well as water vapor, dust particles, and other microscopic particles. It acts as a natural shield for the Earth, as it burns up meteors due to friction. It also helps to reflect sound and light waves, which makes radio and television transmission possible.
  • 2. Hydrosphere
    The Hydrosphere is the part of the Earth's surface covered by water, which is about 71% of the total area. It includes all the oceans, seas, lakes, and rivers. About 97% of the water on Earth is saline and is found in the oceans. The hydrosphere is crucial for the existence of life. Oceans provide a large amount of precious minerals like manganese and iron, and are a source of food. They also serve as major waterways for trade.
  • 3. Importance of Lithosphere
    The Lithosphere is the solid upper layer of the Earth, which is essential for human life. It provides the ground for our homes, farming, and industries. It is the source of minerals, crude oil, and various crops. Mountains and plains on the lithosphere are vital for economic activities and serve as habitats for wildlife. In essence, the lithosphere is the very foundation of our existence, providing food and shelter.