CLASS 10TH SCIENCE CBSE TOP 30 MOST EXPECTED QUESTION ANSWER ANNUAL EXAM 2026
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Q1. What is photosynthesis?
Answer: Photosynthesis is the process by which green plants prepare their food using carbon dioxide, water and sunlight in the presence of chlorophyll.
Q2. Write the balanced chemical equation for respiration.
Answer: C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
Q3. Define acid and base.
Answer: Acid: A substance that produces H⁺ ions in aqueous solution. Base: A substance that produces OH⁻ ions in aqueous solution.
Q4. What is pH scale?
Answer: pH scale is used to measure the acidic or basic nature of a solution. Its value ranges from 0 to 14.
Q5. Name the gas evolved when zinc reacts with hydrochloric acid.
Answer: Hydrogen gas (H₂).
Q6. What is oxidation?
Answer: Oxidation is the process in which a substance gains oxygen or loses hydrogen.
Q7. Define reduction.
Answer: Reduction is the process in which a substance loses oxygen or gains hydrogen.
Q8. What is homologous series?
Answer: A series of organic compounds having the same functional group and similar chemical properties is called homologous series.
Q9. What is the function of stomata?
Answer: Stomata help in exchange of gases and transpiration in plants.
Q10. Define biodegradable waste.
Answer: Waste that can be decomposed by microorganisms is called biodegradable waste.
Q11. What is ozone layer?
Answer: Ozone layer is a protective layer present in the stratosphere which absorbs harmful ultraviolet rays of the sun.
Q12. Name the SI unit of electric current.
Answer: Ampere (A).
Q13. State Ohm’s Law.
Answer: At constant temperature, the current flowing through a conductor is directly proportional to the potential difference across its ends.
Q14. What is resistance?
Answer: Resistance is the opposition offered by a conductor to the flow of electric current.
Q15. Define electric power.
Answer: Electric power is the rate at which electrical energy is consumed.
Q16. What is refraction of light?
Answer: Refraction of light is the bending of light when it passes from one medium to another.
Q17. Name the mirror used as rear-view mirror.
Answer: Convex mirror.
Q18. What is magnification?
Answer: Magnification is the ratio of height of image to height of object.
Q19. Define focal length.
Answer: The distance between the pole and the focus of a mirror is called focal length.
Q20. What is dispersion of light?
Answer: Splitting of white light into its constituent colours is called dispersion of light.
Q21. What is heredity?
Answer: Heredity is the transmission of traits from parents to offspring.
Q22. Define variation.
Answer: Differences in traits among individuals of the same species are called variation.
Q23. What is evolution?
Answer: Evolution is the gradual change in organisms over a long period of time.
Q24. Name the hormones secreted by pancreas.
Answer: Insulin and Glucagon.
Q25. What is reflex action?
Answer: An immediate and automatic response to a stimulus is called reflex action.
Q26. What is biodegradable waste example?
Answer: Vegetable peels, paper, leaves.
Q27. What is non-biodegradable waste?
Answer: Waste that cannot be decomposed by microorganisms is called non-biodegradable waste.
Q28. What is ecosystem?
Answer: An ecosystem is a community of living organisms interacting with their physical environment.
Q29. Define food chain.
Answer: A sequence of organisms through which energy is transferred is called food chain.
Q30. What is natural resource?
Answer: Resources obtained from nature and used by humans are called natural resources.
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