Class 9 Earth as a Planet Mock Test (ICSE)

Topics in Earth as a Planet

• Earth's shape and size
• Unique features of the Earth
• The Earth as a habitable planet

Earth as a Planet practice questions with answers

1. Q1Multiple choice·1 mark
   Why is the Earth frequently referred to as the 'Blue Planet'?

   1. (a)Because it is the closest planet to the Sun
   2. (b)Because it receives blue light scattered directly from space
   3. (c)Because about $71\%$ of its surface is covered with water
   4. (d)Because its atmosphere contains dense water vapor
   Show answer and step marks

   1. Correct option: (c) Because about $71\%$ of its surface is covered with water+1

   Answer: (c)
2. Q2Multiple choice·1 mark
   Which unique condition plays a vital role in maintaining moderate temperatures on Earth, preventing extreme fluctuations between day and night?

   1. (a)Presence of the ozone layer
   2. (b)The moderating effect of water bodies and the atmosphere
   3. (c)Geothermal heat released from the core
   4. (d)High concentration of carbon dioxide in polar regions
   Show answer and step marks

   1. Correct option: (b) The moderating effect of water bodies and the atmosphere+1

   Answer: (b)
3. Q3Multiple choice·1 mark
   Which of the following factors is primarily responsible for retaining the Earth's atmosphere and making it habitable?

   1. (a)High speed of planetary rotation
   2. (b)Appropriate gravitational pull of the Earth
   3. (c)Strong magnetic field of the Moon
   4. (d)Presence of uniform cloud cover
   Show answer and step marks

   1. Correct option: (b) Appropriate gravitational pull of the Earth+1

   Answer: (b)
4. Q4Multiple choice·1 mark
   What is the true geometrical shape of the Earth best described as?

   1. (a)Oblate spheroid
   2. (b)Perfect sphere
   3. (c)Prolate spheroid
   4. (d)Cylindrical body
   Show answer and step marks

   1. Correct option: (a) Oblate spheroid+1

   Answer: (a)
5. Q5Long answer·4 marks
   State four unique features of the Earth that distinguish it from other planets in the solar system and enable it to sustain life.
   Show answer and step marks

   1. First feature, any one of: abundant liquid water covering about $71\%$ of the surface; an atmosphere rich in nitrogen and oxygen that supports life; an ozone layer that blocks harmful ultraviolet rays; a moderate temperature range due to its suitable distance (about $150$ million km) from the Sun; a biosphere where land, water and air interact; or any other valid feature, briefly explained.+1
   2. Second feature, a different one from the same list.+1
   3. Third feature, a different one from the same list.+1
   4. Fourth feature, a different one from the same list.+1

   Answer: Any four of: abundant liquid water; a life-supporting atmosphere of nitrogen and oxygen; a protective ozone layer; moderate temperatures due to its distance from the Sun; a biosphere where land, water and air interact.
6. Q6Long answer·4 marks
   Answer the following questions: (a) Explain how the Earth's precise distance from the Sun helps maintain temperatures suitable for the survival of life. [$2$] (b) Define the biosphere and explain why the interaction among the lithosphere, atmosphere, and hydrosphere makes it a unique feature of Earth. [$2$]
   Show answer and step marks

   1. Stating that Earth is located at an optimal distance from the Sun (about $150$ million km), often referred to as the habitable or Goldilocks zone.+1
   2. Explaining that this ideal distance prevents extreme heat or freezing cold, maintaining moderate surface temperatures.+1
   3. Defining the biosphere as the narrow zone of contact where land, water, and air interact to sustain life.+1
   4. Explaining that the coexistence and harmonious interaction of these three realms are exclusive to Earth, enabling a rich diversity of life not found elsewhere in the solar system.+1

   Answer: (a) Earth is about $150$ million km from the Sun, in the habitable zone, so it is neither too hot nor too cold; temperatures stay moderate and water stays liquid. (b) The biosphere is the narrow zone where land, water and air meet and support life; this interaction is found only on Earth, which makes it unique.

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