Curiosity Class 8 Science Chapter 13 Our Home: Earth, a Unique Life Sustaining Planet Case Study Questions

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Last Updated on January 20, 2026 by XAM CONTENT

Hello students, we are providing case study questions for Class 8 Science. Case study questions are the new question format that is introduced in CBSE board. The resources for case study questions are very less. So, to help students we have created chapterwise case study questions for Class 8 Science. In this article, you will find case study questions for CBSE Class 8 Science chapter 13 Our Home: Earth, a Unique Life Sustaining Planet.

Chapter	Our Home: Earth, a Unique Life Sustaining Planet
Type of Questions	Case Study Questions
Nature of Questions	Competency Based Questions
Board	CBSE
Class	Class 8
Subject	Maths
Useful for	Class 12 Studying Students
Answers provided	Yes
Difficulty level	Mentioned
Important Link	Class 8 Science Chapterwise Case Study

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Case Study Questions on Our Home: Earth, a Unique Life Sustaining Planet

We hope the given case study questions for Our Home: Earth, a Unique Life Sustaining Planet Class 8 helps you in your learning.

Case Study 1:

A student undertakes an Activity to investigate the characteristics of planets in our solar system and determine what makes Earth unique. Using library resources, the student compiles data into a table (Table 13.2) comparing the average temperature, radius, and atmospheric presence of Mercury, Venus, and Earth. The data reveals a general trend where planets become colder as they move away from the Sun. However, a significant anomaly is observed: Venus, the second planet, has an average temperature of 450∘C, making it hotter than Mercury (170∘C), which is closest to the Sun. The student also notes that Earth’s average temperature of 15∘C places it in a specific zone called the ‘Goldilocks zone’.

Questions

1. Based on the data collected in Activity (see Table), what is the primary scientific reason for the anomaly where Venus is hotter than Mercury despite being further from the Sun?
A. Venus has a larger radius than Mercury, generating more internal heat.
B. Venus is located within the ‘Goldilocks zone’.
C. Venus has a thick atmosphere rich in carbon dioxide that traps heat.
D. Mercury has a thick atmosphere that reflects all solar radiation.

Question Type: MCQ
Difficulty Level: Medium

Ans. C. Venus has a thick atmosphere rich in carbon dioxide that traps heat.

Explanation: Venus is the hottest planet not because of its distance, but because its “thick atmosphere traps heat” via the greenhouse effect, specifically due to gases like carbon dioxide. Mercury, in contrast, has no atmosphere, so it cannot trap heat in the same way.

2. (Conceptual) The student observes that Earth has a specific size (radius). If Earth were significantly smaller (like Mercury) but had the same density, how would this physically affect the atmosphere and the potential for life?

Question Type: Conceptual
Difficulty Level: Medium

Ans. If Earth were much smaller, its gravity would be too weak to hold onto the gases in the atmosphere.

Explanation: The size of the planet determines its gravitational pull. If Earth were much smaller, “its gravity would have been too weak to hold on to the gases in our atmosphere, and they would have escaped into space”. Without an atmosphere, life as we know it would not be supported because the atmosphere provides oxygen for breathing, carbon dioxide for photosynthesis, and protection from UV rays

3. The “Habitable Zone” is defined by the distance from a star where water remains liquid. Using the principles of this zone, explain what would happen to the hydrosphere if Earth were moved to the orbital position of Venus, and what would happen if it were moved to the orbital position of Mars (assuming current atmospheric conditions remain constant initially).

Question Type: Analytical
Difficulty Level: Medium

Ans. At Venus’s Position: The water would evaporate.

At Mars’s Position: The water would freeze.

Explanation: The habitable zone (Goldilocks zone) is the specific range of distances where temperature allows water to exist in liquid form, which is essential for life. Moving out of this zone transitions water into either gas (vapour) or solid (ice), neither of which supports the evolution of life in the same way liquid water does.

4. The student compares the warming of Earth to a glass greenhouse used for plants (See Fig.). Explain the fundamental difference in the mechanism of how heat is trapped in Earth’s atmosphere versus how it is trapped in a plant greenhouse.

Curiosity Class 8 Science Chapter 13 Our Home: Earth, a Unique Life Sustaining Planet Case Study Questions-3

Question Type: Conceptual
Difficulty Level: Medium

Ans. Earth’s Atmosphere: Gases like carbon dioxide trap heat by absorbing the radiation given off by the Earth after it is warmed by the Sun

Plant Greenhouse: It traps heat because it is a closed physical space (usually with glass walls). It heats up, and the physical barrier prevents the warm air from escaping or mixing with cooler outside air

Explanation: While both systems result in warming, the mechanisms differ: one is radiative absorption (atmosphere), and the other is preventing air circulation/convection (glass greenhouse).