CBSE Class 10 Science Preboard Paper Set 1(Radiant Resolve: The Final Science Showdown)

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CBSE Class 10 Science Preboard Paper

CLASS – X Year: 2025-2026

SUBJECT – Science (086)

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General Instructions: Class 10 Science Preboard Paper

Please read the following instructions very carefully and strictly follow them: Class 10 Science Preboard Paper

(i) This question paper contains 39 questions. All questions are compulsory. Class 10 Science Preboard Paper

(ii) The question paper is divided into five sections – Sections A, B, C, D, and E. Class 10 Science Preboard Paper

(iii) Section A – questions number 1 to 16 are multiple-choice type questions. For Questions number 17 to 20, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below. Each question carries 1 mark. Class 10 Science Preboard Paper

(iv) Section B – questions number 21 to 26 are very short answer-type questions. Each question carries 2 marks. Each question carries 2 marks. The answer to these questions should be in the range of 30 to 50 words. Class 10 Science Preboard Paper

(v) Section C – Questions No. 27 to 33 are Short Answer type questions. Each question carries 3 marks. The answer to these questions should be in the range of 50 to 80 words. Class 10 Science Preboard Paper

(vi) Section D – Questions No. 34 to 36 are long-answer type questions. Each question carries 5 marks. The answer to these questions should be in the range of 80 to 120 words. Class 10 Science Preboard Paper

(vii) Section E – Questions No. 37 to 39 are of 3 source-based/case-based units of assessment carrying 4 marks each with sub-parts. Class 10 Science Preboard Paper

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Section A (1 Mark Each)

1. During a lab experiment, mixing dilute sulphuric acid with sodium carbonate produces brisk effervescence. The gas evolved is likely to:
   1. Turn lime water milky
   2. Burn with a pop sound
   3. Support combustion
   4. Form a brown precipitate
2. A compound used in baking releases gas when heated and neutralizes acids in the stomach. Its dual behavior suggests:
   1. Amphoteric nature
   2. Weak base with thermal instability
   3. Strong acid with oxidizing property
   4. Neutral salt with catalytic action
3. A metal fails to react with cold water but displaces iron from iron sulphate. Its position in the reactivity series is most likely:
   1. Below hydrogen
   2. Between iron and copper
   3. Above iron but below zinc
   4. Above sodium
4. A hydrocarbon with triple bonds and two carbon atoms belongs to:
   1. Alkane series
   2. Alkene series
   3. Alkyne series
   4. Aromatic series
5. A plant exposed to unilateral light bends toward the source. This response is governed by:
   1. Redistribution of auxin
   2. Increase in gibberellin
   3. Reflex arc activation
   4. Genetic mutation
6. A person with elevated blood sugar levels is prescribed insulin. The hormone acts by:
   1. Stimulating adrenaline
   2. Enhancing glucose absorption
   3. Suppressing thyroxine
   4. Blocking nerve impulses
7. A sudden withdrawal of the hand from a hot object involves:
   1. Voluntary coordination
   2. Reflex pathway via the spinal cord
   3. Hormonal feedback
   4. Cerebral decision-making
8. Asexual reproduction in multicellular algae like Spirogyra occurs through:
   1. Bud formation
   2. Fragmentation
   3. Binary fission
   4. Sporulation
9. A child inherits dimples from one parent and not the other. This trait expression is governed by:
   1. Hormonal dominance
   2. Environmental triggers
   3. Dominant-recessive allele interaction
   4. Reflex coordination
10. A concave mirror forms a magnified, virtual image. The object must be placed:
    1. Beyond the centre of curvature
    2. Between pole and focus
    3. At focus
    4. At infinity
11. A lens diverges parallel rays and forms a virtual image. This lens is:
    1. Convex
    2. Concave
    3. Cylindrical
    4. Bifocal
12. A wire with high resistivity is used in heating appliances. Its selection is justified by:
    1. Efficient current flow
    2. Minimal heat loss
    3. High thermal conversion
    4. Low voltage requirement
13. A current-carrying conductor placed perpendicular to a magnetic field experiences a force. The direction is predicted using:
    1. Fleming’s Left Hand Rule
    2. Right Hand Thumb Rule
    3. Ampere’s Law
    4. Lenz’s Law
14. A compost pit shows rapid decomposition of kitchen waste. The process is facilitated by:
    1. Non-biodegradable substances
    2. Anaerobic bacteria
    3. Synthetic enzymes
    4. Biodegradable matter
15. A refrigerator emits gases that degrade ozone. The compound responsible is:
    1. CO₂
    2. CFCs
    3. NO₂
    4. CH₄
16. A green plant is kept in a brightly lit area. The gas that will be most abundant around the plant is:
    (a) Carbon dioxide
    (b) Oxygen
    (c) Nitrogen
    (d) Water vapour

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🔹 Assertion & Reason (1 mark each)

(A) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A). Class 10 Science Preboard Paper
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). Class 10 Science Preboard Paper
(C) Assertion (A) is true, but Reason (R) is false. Class 10 Science Preboard Paper
(D) Assertion (A) is false, but Reason (R) is true. Class 10 Science Preboard Paper

17. Assertion: Sodium reacts explosively with water.
    Reason: Sodium has low ionization energy and high reactivity.
    
18. Assertion: DNA replication ensures trait continuity.
    Reason: Replication introduces mutations for evolution.
    
19. Assertion: Convex lenses always form real images.
    Reason: Convex lenses converge rays at a point.
    
20. Assertion: AC is preferred over DC for transmission.
    Reason: AC can be transformed to different voltages easily.
    

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🔹 Section B – Very Short Answer (2 marks each)

21. A reaction between quicklime and water releases heat. Represent the reaction and classify it based on energy change and product formation.
22. A solution turns red litmus blue and shows a pH above 7. Interpret its chemical nature and suggest a real-life implication.
23. Ionic compounds exhibit high melting points. Justify this property using electrostatic force concepts.
24. Transpiration contributes to water movement in plants. Link this to the cohesion-tension theory and its physiological relevance.
25. Reproductive health influences population dynamics. Propose a preventive strategy and its societal impact.
26. Stars twinkle while planets don’t. Relate this to atmospheric refraction and apparent position shifts.

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🔹 Section C – Short Answer (3 marks each)

27. A metal reacts with steam but not with cold water. Predict its position in the reactivity series and justify with a balanced equation.
28. Enzymes catalyze digestion. Compare their role in the oral and gastric phases with examples.
29. Reflex actions bypass conscious control. Illustrate the neural pathway using a real-life stimulus-response example.
30. An object is placed 10 cm from a concave mirror of focal length 15 cm. Construct a ray diagram and describe the image formed.
31. A wire of resistance 5Ω carries 2A current. Apply Ohm’s law to determine voltage and interpret the result in terms of energy transfer.
32. A solenoid behaves like a bar magnet. Explain the magnetic field pattern and its practical application in devices.
33. Waste segregation is essential. Differentiate biodegradable and non-biodegradable substances with examples and disposal challenges.

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🔹 Section D – Long Answer (5 marks each)

34. Ethanol burns with a blue flame and is miscible in water.

• Represent the combustion reaction.
• Discuss two physical properties.
• Highlight two uses in daily life.
• Evaluate its role as a clean fuel.

35. Kidneys regulate body fluid composition.

• Describe the structure of a nephron.
• Explain filtration and reabsorption.
• Analyze how the kidneys maintain water balance.

36. A household uses two 100W bulbs and one 200W fan for 5 hours daily.

• Calculate daily energy consumption.
• Estimate the monthly cost at ₹6/unit.
• Recommend two strategies to reduce power usage.

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🔹 Section E – Source/Case-Based Questions (4 marks each)

37. A water treatment plant uses a white powder that releases chlorine slowly. During the monsoon, its usage increases due to a rise in waterborne diseases. The powder is stored in airtight containers, and pH levels are monitored to prevent pipe corrosion.

Respond to the following based on the passage:

1. Identify the compound and infer its chemical behavior.
2. Link seasonal variation to microbial activity and chemical demand.
3. Justify the need for pH control in treated water.
4. Evaluate the reason for airtight storage from a chemical stability perspective.

38. Riya notices her younger brother squinting at distant objects in class but reading books comfortably. An optometrist examines the curvature of the eye lens and prescribes corrective lenses to adjust the focal length. Curious about optics, Riya conducts an experiment using a convex lens and a candle to explore image formation at varying distances. She observes that the image changes in size and orientation depending on the candle’s position relative to the lens.

Respond to the following based on the passage:

1. Infer the nature of the visual condition affecting Riya’s brother and the type of lens prescribed.
2. Relate the concept of focal length to the clarity of distant vision in the human eye.
3. Interpret the variation in image characteristics observed during Riya’s experiment.
4. Evaluate how the principles of refraction support the use of corrective lenses in vision therapy.

39.  The setup below is used to carry out a reaction between ferrous sulphate crystals in a boiling tube.

Study the diagram and answer the following questions:

1. Identify the gas evolved.
2. Write the chemical equation for the reaction taking place.
3. What is the nature of this reaction?

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