CBSE Class 10 Science Half Yearly Exam 2025 Most Important Questions

Are you appearing for Class 10th half yearly this year? If yes, then you are required to have a good understanding of all the important topics, as well as the questions that are highly likely to appear this year. In this article, we will be discussing the CBSE class 10 Science half yearly exam 2025 most important questions. Know that while exact questions like these can be asked in the exam, they can also come in some other languages. Hence, we advise you to not only solve these questions but also understand them thoroughly. Moreover, as per the previous year trends, the topics that can be considered important include types of reactions, balancing, etc in Chemical Reactions & Equations, properties, reactivity, ionic compounds, etc in metals & non-metals, nutrition, respiration, excretion, etc in life processes etc. Read on to know more details about the CBSE Class 10 Science half yearly most important questions 2025.

CBSE Class 10 Science Half Yearly Exam 2025 Most Important Topics

With the half yearly of class 10th being around the corner, you need to have a good knowledge of all the important topics of all the subjects. In the table below, we have mentioned the important topics CBSE class 10th Science half yearly exam 2025:

CBSE Class 10 Science Half Yearly Exam 2025 Most Important Questions

Given below are the most important questions for the CBSE class 10th Science half yearly exam 2025:-

Q1. A solution of a substance ‘X’ is used for whitewashing.

1. Name the substance ‘X’ and write its formula.
2. Write the reaction of the substance ‘X’ named in (a) with water

Q2. What does one mean by exothermic and endothermic reactions? Give examples.

Q3. What is the law of conservation of mass? How is it demonstrated in a chemical reaction?

Q4. What are the different types of chemical reactions?

Q5. What do you mean by a precipitation reaction? Explain by giving examples.

Q6. What are the major differences between ionic and covalent bonds?

Q7. Explain the structure of the heart and its functioning in detail.

Q8. In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.

Q9. Explain the following in terms of gain or loss of oxygen with two examples each:-

1. Oxidation
2. Reduction

Q10. What is the importance of the carbon cycle in the environment?

Q11. Explain Mendel’s laws of inheritance with an example.

Q12. What are plant hormones? Name two and their functions.

Q13. Define pH. What is the pH of neutral water? How does pH change when mixing an acid/base?

Q14. Describe the law of reflection. Draw ray diagrams for a plane mirror / concave mirror.

Q15. What is a reflex arc? List its components and explain with an example.

Q16. What is the importance of sustainable management of natural resources?

Q17. What is corrosion? Why does it happen? How can it be prevented?

Q18. The electronic configuration of an element is 2,8,2. Is it a metal or a non‑metal? Justify.

Q19. What is a neutralisation reaction? Give an example.

Q20. What is meant by the term “water of crystallisation”? Name a compound that contains it.

Q21. Why do acids not show acidic behaviour in the absence of water?

Q22. Explain why sodium is stored in kerosene.

Q23. What is an alloy? Give two examples.

Q24. Why do ionic compounds have high melting points?

Q25. What is peristalsis? Where does it occur in the human body?

Q26. Why are villi present in the small intestine?

Q27. Differentiate between reflex action and walking.

Q28. Name the parts of the human brain and state the function of the cerebellum.

Q29. What is the role of DNA in reproduction?

Q30. Differentiate between sexual and asexual reproduction.

Q31. Name the reproductive parts of a flower.

Q32. What is the difference between genotype and phenotype?

Q33. Define variation. How does it help in evolution?

Q34. Draw a ray diagram for the image formed by a convex lens when the object is between F and 2F.

Q35. Define the principal focus of a concave mirror.

Q36. What is accommodation of the eye?

Q37. State Ohm’s Law.

Q38. Write the formula for the equivalent resistance of resistors in parallel.

Q39. What is the SI unit of electric power?

Q40. Why does the sky appear blue?

Q41. Draw magnetic field lines around a straight current-carrying conductor.

Q42. What happens when a current-carrying conductor is placed in a magnetic field?

Q43. State the function of a fuse in an electric circuit.

Q44. In a reaction of an aqueous solution of barium chloride with an aqueous solution of sodium sulphate, the aqueous solution formed will be:-

1. BACl2
2. BaSO4

Q45. A solution turns red litmus blue. Its pH is likely to be:

1. 1
2. 4
3. 5
4. 10

Q46. Which of the following types of medicines is used for treating indigestion?

1. Antibiotic
2. Analgesic
3. Antacid
4. Antiseptic

Q47. Which of the following is a displacement reaction?

1. NaOH+HCl→NaCl+H2O
2. AgNO3​+NaCl→AgCl+NaNO3​
3. Zn + CuSO4 →ZnSO4 + Cu
4. CaCO3​→CaO+CO2​

Q48. The pH value of a strongly basic solution is:

1. 1
2. 5
3. 7
4. 13

Q49. Which metal is most reactive?

1. Copper
2. Iron
3. Zinc
4. Potassium

Q50. The first member of the alkane series is:

1. Ethane
2. Methane
3. Propane
4. Butane

Q51. Which of the following organs is responsible for filtering nitrogenous waste from blood?

1. Liver
2. Heart
3. Kidney
4. Lungs

Q52. Which process occurs in the mitochondria?

1. Photosynthesis
2. Respiration
3. Excretion
4. Digestion

Q53. Which of the following compounds will give a sooty flame?

a) CH₄

b) C₂H₆

c) C₃H₈

d) C₆H₆

Preparing for the CBSE class 10 Science half yearly exam requires more than just memorisation - it requires a deep understanding of the key concepts, practical applications, and familiarity with the exam pattern. The questions and topics provided above have been curated based on the latest syllabus and previous exam trends to help you focus on what matters most. However, remember that questions may be rephrased or asked in different formats, so understanding the logic behind each answer is essential. Go through your NCERT textbook thoroughly, solve exemplar problems, and practice diagrams, chemical equations, and numericals regularly. A balanced and smart study approach, along with consistent revision, will not only help you score well in your half yearly exams but also lay a strong foundation for the final board exams.