🌍 Chapter 21: Space & Environment – Constructed Response
Prepared by Muhammad Tayyab, Subject Specialist Physics, Govt Christian High School Daska. Based on PECTAA 2026 syllabus (National Curriculum 2023).
📖 What's Inside: This section covers 5 constructed response questions from Chapter 21 Space and Environment including gas giants density, atmospheric composition and surface temperature, Coriolis effect, geothermal activity, and background radiation. Each question is presented with a precise answer as per the official PECTAA 2026 Physics curriculum. Perfect for Punjab Boards (Lahore, Gujranwala, Multan, etc.) and all BISE boards across Pakistan.
📚 Related Resources – Chapter 21
Space and Environment covers the Sun, nuclear fusion, orbital mechanics, cyclones, global warming, background radiation, and radiation safety.
📝 Constructed Response Questions with Answers
21.1 Why do gas giants like Jupiter, despite their larger size, have lower densities than rocky planets such as Earth and Mars? What does this tell us about their internal structure?
Answer: Gas giants have lower densities because they are composed mostly of lightweight hydrogen and helium, whereas rocky planets have dense, solid metallic cores. This indicates that gas giants are primarily gaseous, unlike the solid structures of rocky planets.
✅ Gas giants: mostly H and He → low density. Rocky planets: solid metallic cores → high density.
21.2 If two planets receive the same amount of sunlight but have different atmospheric compositions, why might their surface temperatures still differ significantly?
Answer: Surface temperatures can differ because atmospheric compositions and greenhouse gases dictate how much heat is trapped. A thick atmosphere with greenhouse gases traps more heat (leading to higher temperatures), while a thin atmosphere allows heat to escape.
✅ Atmospheric composition & greenhouse gases determine heat trapping.
21.3 How does the coriolis effect play a role in creating the spiraling motion of cyclones, and what might happen to cyclone formation if the Earth stopped rotating?
Answer: The Coriolis effect deflects moving air around low-pressure areas, causing a spinning motion (counterclockwise in the northern hemisphere, clockwise in the southern). If the Earth stopped rotating, this effect would cease, and cyclones would not form their characteristic spiraling motion.
✅ Coriolis effect causes spinning (counterclockwise/clockwise). No rotation → no spiraling cyclones.
21.4 Compare the ways radiation, conduction, and convection each contribute to geothermal activity. Why is convection considered the primary driver of tectonic plate motion?
Answer: Radiation, conduction, and convection transfer the Earth's internal heat toward the surface. Convection is the primary driver of tectonic plate motion because heat from the interior causes mantle material to rise, cool, and sink, creating convection currents that move the plates.
✅ Convection currents (rise, cool, sink) drive tectonic plate motion.
21.5 Explain why background radiation is always present in our environment and how cosmic and terrestrial sources balance each other despite fluctuations in human activity.
Answer: Background radiation is a constant, low-level radiation present from natural sources (cosmic rays and Earth's crust) and human activities. Cosmic and terrestrial sources maintain a steady baseline that ensures consistency despite fluctuations in human activity.
✅ Natural sources (cosmic + terrestrial) maintain steady baseline.
🌍 Key Concepts – Space & Environment
\[ E = mc^2 \]
Nuclear Fusion Energy
Nuclear Fusion Energy
\[ F = G\frac{m_1m_2}{r^2} \]
Gravitational Force
Gravitational Force
\[ T \propto \frac{1}{r^2} \]
Solar Energy & Distance
Solar Energy & Distance
Unit 10Thermal Physics
Unit 11Transfer of Thermal Energy
Unit 12Waves
Unit 13Sound
Unit 14Light
Unit 15Electrostatics
Unit 16Electricity
Unit 17Electromagnetism
Unit 18Electromagnetic Induction & EM Waves
Unit 19Electronics
Unit 20Atomic and Nuclear Physics
Unit 21✨ Space and Environment
📖 Complete syllabus coverage for Class 10 Physics (PECTAA 2026) – Units 10 to 21
Created by Hira Science Academy | Aligned with PECTAA 2026 Syllabus