Our Home: Earth, a Unique Life-Sustaining Planet — Class 8 MCQs with Answers
Class 8 CBSE Science · Chapter 13
72 practice questions · 24 Easy · 24 Medium · 24 Hard · Updated
Practise the most important Class 8 CBSE Science questions from Chapter 13, "Our Home: Earth, a Unique Life-Sustaining Planet". You get 9 timed quizzes made from 72 NCERT-based MCQs, with answers and explanations. The questions are split into 24 Easy, 24 Medium and 24 Hard. Warm up on the basics, then move on to the exam-level questions that top scorers in CBSE Board exams get right.
To score well in "Our Home: Earth, a Unique Life-Sustaining Planet", focus on clear concepts in physics, chemistry and biology basics. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This helps you stay accurate when time is short, just as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Our Home: Earth, a Unique Life-Sustaining Planet, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 8 Science mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Our Home: Earth, a Unique Life-Sustaining Planet — important questions & MCQs with answers (Class 8 Science)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation.
- Q1Easy
Earth is special among the planets because it:
A.has no atmosphereB.is the largest planetC.supports life✓ CorrectD.is closest to the SunAnswer: C. supports life
Explanation: Earth is the only known planet that supports life — a result of its right distance from the Sun, protective atmosphere and liquid water, not its size or closeness to the Sun.
- Q2Easy
The layer of gases surrounding the Earth is the:
A.oceanB.crustC.coreD.atmosphere✓ CorrectAnswer: D. atmosphere
Explanation: The atmosphere is the blanket of gases surrounding Earth, distinct from the solid crust, core, or the oceans.
- Q3Easy
Burning fossil fuels like coal and oil releases:
A.greenhouse gases such as carbon dioxide✓ CorrectB.pure oxygenC.clean waterD.ozoneAnswer: A. greenhouse gases such as carbon dioxide
Explanation: Burning coal and oil releases carbon dioxide and other greenhouse gases into the air, adding to the natural greenhouse effect.
- Q4Easy
Three big environmental challenges today are climate change, biodiversity loss and:
A.photosynthesisB.pollution✓ CorrectC.gravityD.reflectionAnswer: B. pollution
Explanation: Climate change, biodiversity loss and pollution are the three major environmental challenges facing the planet today.
- Q5Easy
Earth is at just the right distance from the Sun to have:
A.no waterB.moderate temperatures and liquid water✓ CorrectC.boiling seasD.only iceAnswer: B. moderate temperatures and liquid water
Explanation: Earth orbits at a distance from the Sun that keeps temperatures moderate, so water stays liquid rather than boiling away, as on Venus, or freezing solid farther out.
- Q6Easy
The most abundant gas in Earth's atmosphere is:
A.oxygenB.carbon dioxideC.hydrogenD.nitrogen✓ CorrectAnswer: D. nitrogen
Explanation: Nitrogen makes up about 78% of Earth's atmosphere by volume, far more than oxygen (~21%) or the trace gas carbon dioxide.
- Q7Medium
If Earth were much closer to the Sun, its water would likely:
A.boil away✓ CorrectB.stay liquidC.freeze solidD.turn to rockAnswer: A. boil away
Explanation: Moving Earth closer to the Sun would push surface temperatures well past water's boiling point, so the oceans would boil away rather than stay liquid.
- Q8Medium
Earth's moderate temperature comes from its right distance from the Sun AND its:
A.colourB.spin speed onlyC.number of moonsD.atmosphere (greenhouse effect)✓ CorrectAnswer: D. atmosphere (greenhouse effect)
Explanation: Earth's atmosphere traps some outgoing heat through the natural greenhouse effect, which combines with its distance from the Sun to keep temperatures moderate.
- Q9Medium
The greenhouse effect becomes a problem when:
A.extra greenhouse gases trap too much heat✓ CorrectB.there are no greenhouse gasesC.the Sun goes outD.oxygen increasesAnswer: A. extra greenhouse gases trap too much heat
Explanation: The greenhouse effect turns harmful when extra greenhouse gases, beyond the natural balance, trap more heat than the planet needs, pushing temperatures up.
- Q10Medium
The Montreal Protocol (1987) helped by reducing chemicals that:
A.clean the oceansB.warm the SunC.increase oxygenD.damage the ozone layer✓ CorrectAnswer: D. damage the ozone layer
Explanation: The Montreal Protocol (1987) phased out chlorofluorocarbons and similar chemicals that were breaking down the ozone layer.
- Q11Medium
If Earth were much farther from the Sun, its water would likely:
A.boilB.stay the sameC.freeze✓ CorrectD.disappearAnswer: C. freeze
Explanation: Moving Earth farther from the Sun would drop temperatures below water's freezing point, turning liquid water to ice rather than leaving it unchanged.
- Q12Hard
Which factor is NOT one of the reasons Earth can support life?
A.it has the most moons✓ CorrectB.its right distance from the SunC.its atmosphereD.its magnetic fieldAnswer: A. it has the most moons
Explanation: Earth's habitability comes from its right distance from the Sun, its atmosphere and its magnetic field, not from having the most moons, which plays no role in supporting life.
- Q13Hard
The natural greenhouse effect is beneficial because without it Earth would be:
A.exactly the sameB.too hotC.much too cold for life✓ CorrectD.made of ice and fireAnswer: C. much too cold for life
Explanation: Without any greenhouse effect to trap heat, Earth's average temperature would plunge far below freezing, making it much too cold to support life.
- Q14Hard
The chain leading to climate change is: burning fossil fuels →
A.less CO₂, coolingB.more CO₂, more heat trapped, global warming, climate change✓ CorrectC.more oxygen, no changeD.more ozone, coolingAnswer: B. more CO₂, more heat trapped, global warming, climate change
Explanation: Burning fossil fuels releases extra carbon dioxide, which traps more heat in the atmosphere, driving global warming and the resulting shifts in climate.
Key concepts: Our Home: Earth, a Unique Life-Sustaining Planet (Class 8 Science)
This closing chapter asks what makes the Earth 'just right' for life. Its distance from the Sun places it in the habitable, or Goldilocks, zone where liquid water — essential for life — can exist. Its size gives it enough gravity to hold an atmosphere of mostly nitrogen and oxygen, whose natural greenhouse effect keeps the planet warm. The ozone layer blocks harmful ultraviolet rays and the magnetic field shields us from harmful particles from the Sun. But human activities — burning fossil fuels, releasing greenhouse gases, polluting and destroying habitats — are causing global warming, climate change and biodiversity loss, so protecting our unique home is urgent.
- Earth is unique for life
- As far as we know, Earth is the only planet that supports life, thanks to a rare combination of conditions working together.
- Right distance and liquid water
- Earth lies at the right distance from the Sun for moderate temperatures at which water stays liquid — and liquid water is essential for life.
- Habitable (Goldilocks) zone
- The region around a star where a planet is 'not too hot and not too cold' for liquid water; Mars lies at the edge of the Sun's habitable zone.
- Right size and the atmosphere
- Earth is large enough for its gravity to hold on to an atmosphere — the layer of gases around it; a small planet with weak gravity would lose its gases to space.
- Atmosphere composition
- Air is mostly nitrogen (the most abundant gas) and oxygen (which we breathe), with a small amount of carbon dioxide.
- Greenhouse effect
- Gases such as carbon dioxide trap some of the Sun's heat, keeping the Earth warm; without this natural greenhouse effect the Earth would be far too cold for life.
- Ozone layer
- A layer high in the atmosphere that shields the surface by blocking most of the Sun's harmful ultraviolet (UV) rays.
- Magnetic field
- Generated by movement in Earth's core, it acts like a protective shield against harmful charged particles from the Sun.
- Global warming
- The gradual rise in Earth's average temperature, caused mainly by extra greenhouse gases from burning fossil fuels like coal and oil.
- Climate change
- Long-term changes in temperature, rainfall and weather patterns that follow from global warming, with effects such as melting glaciers and rising seas.
- Environmental challenges
- The major threats today are climate change, biodiversity loss and pollution, largely driven by human activities.
- Protecting the planet
- Cutting pollution, using clean energy, planting trees and global agreements like the Montreal Protocol (1987) and the Earth Summit (1992) help protect our home.
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Start this chapter free →Our Home: Earth, a Unique Life-Sustaining Planet — FAQs
What are the key concepts in Class 8 Science Our Home: Earth, a Unique Life-Sustaining Planet?+
This closing chapter asks what makes the Earth 'just right' for life. Its distance from the Sun places it in the habitable, or Goldilocks, zone where liquid water — essential for life — can exist. Its size gives it enough gravity to hold an atmosphere of mostly nitrogen and oxygen, whose natural greenhouse effect keeps the planet warm. The ozone layer blocks harmful ultraviolet rays and the magnetic field shields us from harmful particles from the Sun. But human activities — burning fossil fuels, releasing greenhouse gases, polluting and destroying habitats — are causing global warming, climate change and biodiversity loss, so protecting our unique home is urgent. Key ideas include Earth is unique for life, Right distance and liquid water, Habitable (Goldilocks) zone, Right size and the atmosphere, Atmosphere composition, Greenhouse effect.
What does Class 8 Science Chapter 13 (Our Home: Earth, a Unique Life-Sustaining Planet) cover on XamBaaz?+
It has 72 NCERT-based MCQs on "Our Home: Earth, a Unique Life-Sustaining Planet": 24 Easy, 24 Medium and 24 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE Board exams.
Are these "Our Home: Earth, a Unique Life-Sustaining Planet" questions free to practise?+
Yes. Sign in with Google to practise "Our Home: Earth, a Unique Life-Sustaining Planet" free. Full unlimited access is ₹999/year. One year from the day you pay. You stay in Class 8 till 31 March; on 1 April your account moves up to Class 9 and the rest of your year carries over. No chapter is charged separately.
How should I revise "Our Home: Earth, a Unique Life-Sustaining Planet" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Our Home: Earth, a Unique Life-Sustaining Planet" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Our Home: Earth, a Unique Life-Sustaining Planet" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Our Home: Earth, a Unique Life-Sustaining Planet (Class 8 Science)?+
The questions that matter most test Earth is unique for life, Right distance and liquid water, Habitable (Goldilocks) zone, Right size and the atmosphere, Atmosphere composition, Greenhouse effect. This page shows 14 solved important MCQs with answers and explanations. Sign in to practise all 72 questions on the chapter as timed quizzes.
Is there an online quiz for Our Home: Earth, a Unique Life-Sustaining Planet?+
Yes — Class 8 Science Our Home: Earth, a Unique Life-Sustaining Planet has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.