🌍 Chapter 21: Space & Environment – Exercise Short Questions
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 8 exercise short questions from Chapter 21 Space and Environment including Sun composition, planet comparison factors, global warming and hurricanes, background radiation, safety measures, cyclones, Coriolis effect, and rising sea levels. 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.
📝 Exercise Short Questions with Answers
21.1 What are the two main elements that make up the Sun?
Answer: The Sun contains 74% of hydrogen and 24% of helium along with few other elements.
✅ 74% Hydrogen, 24% Helium.
21.2 What factors are used to compare planets in terms of their characteristics?
Answer: For the study of planets, it is necessary to focus on different factors such as orbital distance, orbital period, density, surface temperature, gravitational field strength, etc. which makes each planet unique.
✅ Orbital distance, orbital period, density, surface temperature, gravitational field strength.
21.3 Explain how global warming increases the intensity of hurricanes.
Answer: Due to rise in the temperature, more heat is absorbed by the ocean which fuels hurricanes, making them stronger and more destructive. Intensity of hurricanes is increased by the warmer ocean waters, with higher wind speeds and heavier rainfall, causing greater damage.
✅ Warmer oceans fuel stronger hurricanes with higher winds and rainfall.
21.4 What is background radiation, and what are its natural sources?
Answer: The radiation that exists around us all the time is known as background radiation. Its natural sources include cosmic rays from space, radioactive materials in the Earth's crust like uranium and radon, and tiny amounts of radiation in our food and bodies.
✅ Cosmic rays, uranium/radon in Earth's crust, food & bodies.
21.5 Name three safety measures used to handle radioactive materials safely.
Answer: The text specifically mentions protective wear, limited exposure, and storing or handling radioactive materials safely.
✅ Protective wear, limited exposure, safe storage/handling.
21.6 Why do cyclones weaken when they move over land?
Answer: Cyclones start to weaken when they move over land or colder water because they can no longer get warm, moist air, which acts like fuel for the storm. Without this energy, the storm loses its strength, the winds become weaker, and the cyclone slowly fades away.
✅ Lose warm, moist air (fuel) over land or cold water.
21.7 How does the Coriolis Effect influence the movement of cyclones?
Answer: Because the Earth is spinning, this moving air does not go in a straight line. Instead, it starts to spin around the low-pressure area. This effect is called the Coriolis effect. In the northern hemisphere, the air spins anticlockwise, while in the southern hemisphere, it spins clockwise.
✅ Causes spinning (anticlockwise in north, clockwise in south).
21.8 What is the primary cause of rising sea levels due to global warming?
Answer: Ice begins to melt and seawater expands due to rise in the temperatures. This results in higher sea levels.
✅ Melting ice + seawater expansion → higher sea levels.
🌍 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