SCIENCE CLASS- 8
CHAPTER-1 (Exploring the Investigative World of Science)
Question 1. What is meant by curiosity in science?
Answer: Curiosity in science is the desire to know and understand things around us. It encourages us to ask questions and explore the world scientifically.
Question 2. How does science usually begin?
Answer: Science usually begins with wonder and simple questions about the world around us. Questions such as why dough rises or why a puri puffs up can lead to scientific investigations.
Question 3. What is meant by investigation in science?
Answer: Investigation in science means asking focused questions, making careful observations, conducting experiments and using evidence to understand a phenomenon.
Question 4. Why are students called young scientists in this chapter?
Answer: Students are called young scientists because they are encouraged to observe, question, experiment and explain natural phenomena just like scientists do.
Question 5. What do the root and kite symbols in the textbook represent?
Answer:
- Root: Represents a strong foundation of knowledge and careful observation.
- Kite: Represents curiosity, imagination and exploration of new ideas.
Together they remind us to balance observation with creative thinking.
Question 6. Why is careful observation important in science?
Answer: Careful observation helps scientists collect accurate information about an object or event. It forms the basis of scientific investigations and conclusions.
Question 7. Give two examples of scientific questions mentioned in the chapter.
Answer:
- Why is one side of a puri thinner than the other?
- Why does dough rise?
Question 8. How do microbes affect our lives?
Answer:
- Some microbes help in digestion.
- Some help in producing medicines.
- Some microbes cause diseases and infections.
Question 9. How do nutritious food and exercise help us?
Answer: Nutritious food and regular exercise help us remain healthy and strengthen our body's ability to fight infections.
Question 10. What are the two important effects of electric current mentioned in the chapter?
Answer:
- Heating effect of electric current.
- Magnetic effect of electric current.
Question 11. How do forces affect objects?
Answer: Forces can make an object move, stop, speed up, slow down or change its direction.
Question 12. What is pressure?
Answer: Pressure is the force acting on a unit area of a surface. Differences in pressure can produce breezes, winds and cyclones.
Question 13. What are solids and gases made of?
Answer: Solids and gases are made of tiny particles.
- Particles in solids are closely packed.
- Particles in gases move freely.
Question 14. How are materials classified in science?
Answer:
- Elements
- Compounds
- Mixtures
Question 15. What is a solution? Give one example.
Answer: A solution is a homogeneous mixture formed when one substance dissolves in another.
Example: Sugar dissolved in tea.
Question 16. Why are mirrors and lenses important?
Answer: Mirrors and lenses help us understand the behaviour of light and are used in spectacles, cameras, microscopes and many other devices.
Question 17. What causes the phases of the Moon?
Answer: The phases of the Moon occur because different portions of the Moon are illuminated by sunlight as the positions of the Earth, Moon and Sun change.
Question 18. What is an ecosystem?
Answer: An ecosystem is a system formed by living organisms and their surroundings where they interact with one another and with air, water and sunlight.
Question 19. Why is Earth suitable for life?
Answer:
- Earth is at the correct distance from the Sun.
- Water exists in liquid form.
- Earth has an oxygen-rich atmosphere.
- The atmosphere protects us from harmful ultraviolet rays.
Question 20. What is systematic investigation?
Answer: Systematic investigation is the scientific process of asking questions, making observations, conducting experiments, recording results and drawing conclusions in an organised manner.