NCERT Class 8 Science – Chapter 15: Some Natural Phenomena A. Textbook questions and answers Q1. Which of the following cannot be charged easily by friction? (a) A plastic scale (b) A copper rod (c) An inflated balloon (d) A woollen cloth Answer: (b) A copper rod. Explanation: Copper is a conductor. Charge can move through it and escape through the hand holding it, making it difficult to retain charge by rubbing. Q2. When a glass rod is rubbed with silk cloth, the rod: (a) and the cloth both become positively charged. (b) becomes positively charged while the cloth becomes negatively charged. (c) and the cloth both become negatively charged. (d) becomes negatively charged while the cloth becomes positively charged. Answer: (b) The glass rod becomes positively charged, while the silk cloth becomes negatively charged. Q3. Write T for true and F for false. (a) Like charges attract each other. — False (b) A charged glass rod attracts a charged plastic straw. — True, if they have oppos...

  NCERT Class 8 Science – Chapter 14 Chemical Effects of Electric Current A. Textbook exercise questions and answers Q1. Fill in the blanks. (a) Most liquids that conduct electricity are solutions of ______, ______ and ______. Answer: Acids, bases and salts. (b) The passage of an electric current through a solution causes ______ effects. Answer: Chemical effects. (c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the ______ terminal of the battery. Answer: Negative terminal. (d) The process of depositing a layer of any desired metal on another material by means of electricity is called ______. Answer: Electroplating. Q2. When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason? Answer: The magnetic needle deflects because electric current flows through the circuit. This indicates that the solution conducts electricity. The current produces a magnetic effect arou...

  NCERT Class 8 Science – Chapter 13 Questions and Answers A. Short-answer questions Q1. What makes Earth unique among the planets of our solar system? Answer: Earth supports life because it has liquid water, a suitable temperature, a protective atmosphere, oxygen for respiration and a magnetic field that protects it from many charged particles from the Sun. Q2. Why is Mars unable to support life like Earth at present? Answer: Mars has a very thin atmosphere and lacks stable liquid water on its surface. It also lacks Earth's global magnetic field, making conditions difficult for life as we know it. Q3. What is the habitable zone? Answer: The habitable zone is the region around a star where temperatures may allow liquid water to exist on a planet's surface, provided other necessary conditions are present. Q4. What is the importance of Earth's atmosphere? Answer: Earth's atmosphere provides gases essential for life, helps regulate temperature, supports weather and protect...

  NCERT Class 8 Science – Chapter 12: Questions and Answers Important Questions and Answers Q1. What is a habitat? Answer: A habitat is the natural home or environment of an organism where it gets food, water, shelter and suitable conditions to survive. Q2. What are biotic and abiotic components of an ecosystem? Answer: Biotic components: Living things such as plants, animals and microorganisms. Abiotic components: Non-living things such as air, water, soil and sunlight. Q3. What is an ecosystem? Answer: An ecosystem consists of living organisms and non-living components interacting with one another in a particular area. Q4. What is a food chain? Answer: A food chain is a sequence showing how energy passes from one organism to another through feeding. Example: Grass → Grasshopper → Frog → Snake → Eagle. Q5. Why are plants important in an ecosystem? Answer: Plants produce food through photosynthesis. They provide food and shelter to animals, release oxygen and help maintain the bala...

  NCERT Class 8 Science – Chapter 10: Reaching the Age of Adolescence Important Questions and Answers A. Very Short Answer Questions Q1. What is adolescence? Answer: Adolescence is the period of life when a child undergoes physical, mental and emotional changes and gradually develops towards adulthood. It generally begins around 11 years of age and may continue up to 18 or 19 years. Q2. What is puberty? Answer: Puberty is the stage during adolescence when the body becomes capable of reproduction due to hormonal changes. Q3. What are hormones? Answer: Hormones are chemical substances produced by endocrine glands that regulate various activities of the body. Q4. What is the endocrine system? Answer: The endocrine system is a group of glands that release hormones into the bloodstream to control and coordinate body functions. Q5. Name the male sex hormone. Answer: Testosterone is the main male sex hormone. Q6. Name the main female sex hormones. Answer: Oestrogen is a major female sex h...

  NCERT Class 8 Science – Chapter 9: Reproduction in Animals Important Questions and Answers A. Very Short Answer Questions Q1. What is reproduction? Answer: Reproduction is the biological process by which living organisms produce offspring of their own kind. Q2. What are the two main types of reproduction? Answer: The two main types of reproduction are: Sexual reproduction Asexual reproduction Q3. What is sexual reproduction? Answer: Sexual reproduction is a type of reproduction in which male and female reproductive cells fuse to form a new organism. Q4. What are gametes? Answer: Gametes are reproductive cells. The male gamete is called the sperm, and the female gamete is called the ovum or egg. Q5. What is fertilisation? Answer: Fertilisation is the fusion of a male gamete and a female gamete to form a zygote. Q6. What is a zygote? Answer: A zygote is the single cell formed by the fusion of a sperm and an ovum. Q7. What is an embryo? Answer: An embryo is the early developing stag...

  NCERT Class 8 Science – Chapter 7: Conservation of Plants and Animals Important Questions and Answers A. Very Short Answer Questions Q1. What is deforestation? Answer: Deforestation is the large-scale cutting down of forests and clearing of forest land for other purposes. Q2. Name two causes of deforestation. Answer: Clearing forests for agriculture. Cutting trees for timber and construction. Q3. What is biodiversity? Answer: Biodiversity is the variety of plants, animals and other living organisms found in a particular area. Q4. What is wildlife? Answer: Wildlife refers to animals, birds and other organisms living in their natural habitats. Q5. What is an endangered species? Answer: An endangered species is a species that faces a high risk of becoming extinct. Q6. What is extinction? Answer: Extinction is the permanent disappearance of a species from Earth. Q7. What is a wildlife sanctuary? Answer: A wildlife sanctuary is a protected area where wild animals and their habitats ar...