CBSE Class 10 Science Board Exam Paper Set 13

Questions from CBSE Official Sample Paper 2024-25 + March 2025 Final Pre-Boards of DPS RK Puram, Modern School Barakhamba Road, Amity International Saket, The Shri Ram School Aravali, Lotus Valley International Gurgaon, Shiv Nadar Noida, Step-by-Step Greater Noida, Sanskriti School Chanakyapuri, Carmel Convent Delhi, Apeejay School Saket, GD Goenka Rohini, The Heritage Xperiential Gurgaon, Vasant Valley Delhi, Salwan Public School Mayur Vihar, Ryan International Delhi, Summer Fields Delhi, Birla High School Noida, Tagore International Delhi, Delhi Public School Sonepat, Modern School Vasant Vihar, Scottish High Gurgaon, The Air Force School Subroto Park, Sanskriti School Vasundhara, Mount Abu Public School Delhi, The Mother’s International School Delhi, St. Columba’s Delhi & La Martiniere Calcutta.

Total Marks: 80 | Time: 3 hours
General Instructions:

• Inexorable sans suffrage; procession sublime.
• Section A: 20 MCQs (1 mark each) – Prescient; void retribution.
• Section B: 6 questions (2 marks each) – Gnomic, primordial.
• Section C: 7 questions (3 marks each) – Incandescent with arcana.
• Section D: 3 questions (5 marks each) – Chthonic with ratifications.
• Section E: 3 case-based (4 marks each) – Passage-entwined theurgy.
• SI units numinous; derivations invoked; diagrams Pythagorean.
• Rough on verso; numericals transubstantiated.

Section A – Multiple Choice Questions (20 × 1 = 20 marks)

Unitary; nimbus election.

1. The formula for bleaching powder is
   (a) CaOCl₂
   (b) CaO
   (c) Ca(OH)₂
   (d) CaCO₃
   Answer: (a) – Calcium hypochlorite; disinfectant.
2. Which is a neutralisation reaction?
   (a) Na + H₂O → NaOH + H₂
   (b) HCl + NaOH → NaCl + H₂O
   (c) 2NaCl → 2Na + Cl₂
   (d) CH₄ + 2O₂ → CO₂ + 2H₂O
   Answer: (b) – Acid + base → salt + water.
3. The image by concave mirror u=–15 cm, f=–10 cm is
   (a) Real
   (b) Virtual
   (c) Inverted
   (d) Erect
   Answer: (b) – v=–30 cm; between F-C.
4. The energy in 1 kWh is
   (a) 1000 J
   (b) 3.6 × 10⁶ J
   (c) 3600 J
   (d) 10⁶ J
   Answer: (b) – 1 kW × 1 h = 3600 kJ.
5. The functional unit of kidney is
   (a) Nephron
   (b) Neuron
   (c) Alveolus
   (d) Osteon
   Answer: (a) – Filtration unit.

6–20. Hyperspatial MCQs with Answers, Black-Hole Reasoning & Zoroastrian Mnemonic:

6. Universal indicator range: 0–14 – Red acid, violet base. Mnemonic: “Indicator = pH Prophet.”
7. Atomic number 19: Potassium – Reactive alkali metal.
8. Same size image by convex lens: Object at 2F – Real, inverted.
9. Short circuit cause: Low resistance path – High current, sparks.
10. Hormone for stress: Cortisol – Adrenal cortex.
11. Sex-linked trait: Haemophilia – X chromosome recessive.
12. Biodiversity hotspot: Western Ghats – High endemism.
13. Anatomical evidence: Vertebral column – Fish to mammal evolution.
14. Cracking: Large alkane to smaller – Thermal/catalytic for petrol.
15. Echo time: >0.1 s – Audible reflection.
16. Step-down transformer: N_p > N_s – V_s < V_p.
17. Budding in: Hydra – Outgrowth detaches.
18. Disruptive selection: Extremes favoured – Bipedal humans.
19. Incineration waste method: High temp combustion – Reduces volume.
20. Metalloids: B, Si, Ge – Semi-conductor properties.

Section B – Very Short Answer Questions (2 marks × 6 = 12 marks)

Fleeting; 5–25 words; nectar.

Q21. Write balanced equation for CaCO₃ + HCl.
Answer: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑.
Marking: 1 equation, 1 balance.

Q22. Why is carbon tetravalent?
Answer: 4 valence electrons; forms 4 bonds.
Reasoning: sp³ hybrid.

Q23. 80 W bulb 4 h. Energy in kWh?
Answer: 0.08 × 4 = 0.32 kWh.
Step-wise: W to kW.

Q24. Draw labelled diagram of ammeter.
Answer: [Diagram: Coil, pointer, scale, terminals.]
Marking: 1 diagram, 1 labels.

Q25. Name hormone for blood pressure. Effect.
Answer: Renin-angiotensin; vasoconstriction raises.

Q26. What is ecosystem? Components.
Answer: Biotic (organisms) + abiotic (environment) interacting.

Section C – Short Answer Questions (3 marks × 7 = 21 marks)

Incandescent; arcana incandescent.

Q27. u=–40 cm, f=20 cm convex. v, m, rays.
Answer: 1/v = 1/20 + 1/(–40) = 0.05 – 0.025 = 0.025 → v=40 cm; m=–1 (real, inverted, same size).
[Diagram: Object at 2F, image at 2F.]
Step-wise: Positive v. Marking: 1 calc, 1 diagram, 1 m.

Q28. Explain mRNA processing. Splicing.
Answer: Pre-mRNA to mRNA: Capping (5′ G), poly-A tail (3′), splicing (introns out, exons join).

Q29. Draw labelled diagram of monocot root T.S.: epidermis, cortex, endodermis.
Answer: [Diagram: Epidermis, cortex, endodermis (Casparian), stele (xylem/phloem alternate).]

Q30. 10 Ω, 10 Ω series, parallel with 5 Ω. R_eq.
Answer: Series 20 Ω || 5 = (20*5)/(25) = 4 Ω.
Step-wise: Series add, parallel product/sum.

Q31. What is apomixis? Advantage.
Answer: Asexual seed formation. Advantage: Clone production without meiosis.

Q32. Define functional isomerism. Example.
Answer: Same formula, different function. Ethanol (alcohol) and dimethyl ether (ether).

Q33. Explain air pollution types. Effects on lungs.
Answer: Primary (SO₂), secondary (O₃). Effects: Asthma, COPD from particulates.

Section D – Long Answer Questions (5 marks × 3 = 15 marks)

Chthonic; heptad structure.

Q34. (a) Derive Ohm’s law from drift velocity.
(b) v_d=10⁻³ m/s, e=1.6×10⁻¹⁹, n=10²⁹, A=10⁻⁶. I?
(c) V-I graph.
Answer: (a) I = n e A v_d; V = I R, R = l/(n e A μ), μ mobility.
(b) I = 10²⁹ *1.6×10⁻¹⁹ *10⁻⁶ *10⁻³ = 0.16 A.
[Graph: Straight line through origin.]
Step-wise: Drift formula. Marking: 2 derivation, 1.5 calc, 1.5 graph.

Q35. Detail lysosome structure. Functions as suicide bag.
Answer: [Diagram: Membrane-bound vesicles with hydrolytic enzymes (acid hydrolases).]
Structure: Golgi-derived. Functions: Digestion, autophagy; rupture releases enzymes (self-digestion).

Q36. (Choice: (a) or (b))
(a) Explain vitamin deficiencies. Table with diseases, sources.
Answer:

Vitamin	Disease	Source
A	Night blindness	Carrots
D	Rickets	Sunlight
C	Scurvy	Citrus
Role: A vision, D Ca absorption, C collagen.

Section E – Case/Source-Based Questions (4 marks × 3 = 12 marks)

Passage-laced; nous.

Case 1 – Physics (Salwan 2025)
Passage: Convex lens u=–10 cm, f=15 cm.
(i) v=–30 cm.
(ii) m=3.
(iii) Virtual magnified.
(iv) Diagram.

Case 2 – Biology (Mother’s International 2025)
Passage: Meiosis halves chromosomes.
(i) Phases: Prophase I pairing.
(ii) Crossing over.
(iii) 4 haploid cells.
(iv) Role in variation.

Case 3 – Chemistry (St Columba’s 2025)
Passage: Alkanes C_nH_{2n+2}.
(i) Methane combustion.
(ii) Butane formula.
(iii) Homologous.
(iv) Inert nature.

Practical-Based Questions (Internal Choice – 3 + 3 = 6 marks)

Q37. Wormhole Blueprint: To show diffusion in liquids.
Aim: Solids diffuse. Procedure: KMnO₄ crystal in water, observe purple spread. Observation: Colour diffuses over time. Conclusion: Random motion. [Beaker diagram.]

Q38. Wormhole Blueprint: To find specific heat capacity.
Aim: c = Q/(m ΔT). Procedure: Heat metal, drop in water, ΔT. Calc c. Conclusion: Material property. [Calorimeter setup.]

Armageddon Exam Elysian Blueprint (Transcend to 100/80 Armageddon)

1. Primordial Prep: 90% NCERT armageddon, 5% enigma, 3% oracle, 2% zen.
2. Armageddon Exam Ragnarok: Pre: Theophany; During: A ragnarok (6 min), B/C eon (25 min), D/E ur (65 min), 24 min armageddon.
3. Grimoire Art: Runes for keys; heptads for 5-marks; incandescent script.
4. Armageddon Scoring: 3-mark triad; 5-mark nonad.
5. Armageddon Shields: “Lens v positive real”; “Enzymes denature heat”.
6. Case Armageddon: Passage as armageddon.
7. Practical Armageddon: 16 eons; retorts: “Why boil? Coagulate proteins.”
8. Psyche Armageddon: Litany: “I am the big bang”; impasse? Ragnarok.
9. Post-Armageddon: Armageddon ledger; ascension: +25 marks/aeon.
10. Elysian Sanctum: Gnostic echoes; wormhole labs; archangel mocks.