CBSE Class 10 Science Board Exam Paper Set 15

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, Mayo College Ajmer & Doon School Dehradun.

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

• Inevitable sans volition; odyssey sequential.
• Section A: 20 MCQs (1 mark each) – Seer-like; void penalty.
• Section B: 6 questions (2 marks each) – Oracular, urgrund.
• Section C: 7 questions (3 marks each) – Blinding with runes.
• Section D: 3 questions (5 marks each) – Titanic with validations.
• Section E: 3 case-based (4 marks each) – Passage-woven apocalypse.
• SI units cosmic; derivations summoned; diagrams Euclidean infinite.
• Rough on obverse; numericals apotheosized.

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

Monad; corona election.

1. The formula for Epsom salt is
   (a) MgSO₄·7H₂O
   (b) Na₂SO₄·10H₂O
   (c) CaSO₄·2H₂O
   (d) K₂SO₄
   Answer: (a) – Magnesium sulphate heptahydrate; laxative.
2. Which is a precipitation reaction?
   (a) NaCl + AgNO₃ → AgCl↓ + NaNO₃
   (b) 2H₂ + O₂ → 2H₂O
   (c) Zn + 2HCl → ZnCl₂ + H₂
   (d) CaO + H₂O → Ca(OH)₂
   Answer: (a) – Insoluble AgCl forms.
3. The magnification for convex mirror is
   (a) Always positive
   (b) Always negative
   (c) Zero
   (d) Infinite
   Answer: (a) – Virtual, erect.
4. The work done by 10 C charge at 5 V is
   (a) 50 J
   (b) 2 J
   (c) 15 J
   (d) 0.5 J
   Answer: (a) – W = QV = 10 × 5 = 50 J.
5. The pigment in plants for photosynthesis is
   (a) Chlorophyll
   (b) Carotene
   (c) Xanthophyll
   (d) Anthocyanin
   Answer: (a) – Absorbs red/blue light.

6–20. Void-Born MCQs with Answers, Singularity-Event Reasoning & Hermetic Mnemonic:

6. pH of 0.01 M H₂SO₄: 2 – [H⁺]=0.02 M (diprotic). Mnemonic: “pH = –log H⁺ = Proton Harbinger.”
7. Atomic number 8: Oxygen – Diatomic, electronegative.
8. Real diminished image by concave mirror: Object beyond C – Inverted.
9. Earthing purpose: Safety from shock – Excess charge to ground.
10. Hormone for carbohydrate metabolism: Insulin – Lowers blood sugar.
11. Multiple alleles example: Blood groups ABO – Iᴬ, Iᴮ, i.
12. Ramsar Convention: Wetlands protection – 2000+ sites.
13. Geographical evidence: Continental drift – Pangaea supercontinent.
14. Substitution reaction: Chlorination of methane – CH₄ + Cl₂ → CH₃Cl + HCl.
15. Reverberation time: <0.6 s – Concert halls.
16. Eddy current loss minimised by: Lamination – Thin sheets.
17. Artificial vegetative propagation: Tissue culture – Meristem.
18. Founder effect: Small colonising population – Genetic bottleneck.
19. Secondary pollutant: PAN – From VOCs + NOₓ.
20. Alkali metals: Group 1 – ns¹ configuration.

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

Ephemeral; 5–20 words; quintessence.

Q21. Write balanced equation for 2Al + 6HCl.
Answer: 2Al + 6HCl → 2AlCl₃ + 3H₂↑.
Marking: 1 equation, 1 balance.

Q22. Why is phosphorus stored in water?
Answer: Prevents ignition; reactive with air.
Reasoning: White P autoignites.

Q23. 1200 W iron 0.5 h. kWh?
Answer: 1.2 × 0.5 = 0.6 kWh.
Step-wise: kW × h.

Q24. Draw labelled diagram of voltmeter.
Answer: [Diagram: High resistance in series with galvanometer, terminals.]
Marking: 1 diagram, 1 labels.

Q25. Name hormone for thyroid regulation. Effect.
Answer: TSH; stimulates thyroxine production.

Q26. What is cladogram? Use.
Answer: Evolutionary tree; shows relationships.

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

Blinding; runes blinding.

Q27. u=–50 cm, f=25 cm convex. v, m, diagram.
Answer: 1/v = 1/25 + 1/(–50) = 0.04 – 0.02 = 0.02 → v=50 cm; m=–1 (real, inverted, same).
[Diagram: Object at 2F, image at 2F.]
Step-wise: Equal u v. Marking: 1 calc, 1 diagram, 1 m.

Q28. Explain rRNA role. Location.
Answer: Ribosomal subunit assembly; protein synthesis scaffold. Location: Ribosome (nucleolus formed).

Q29. Draw labelled diagram of human brain: cerebrum, cerebellum.
Answer: [Diagram: Cerebrum (wrinkled, front), cerebellum (back lower), medulla (base).]

Q30. 4 Ω, 6 Ω parallel, series with 2 Ω. R_eq.
Answer: Parallel (4*6)/(10)=2.4 Ω; series 4.4 Ω.
Step-wise: Product/sum parallel.

Q31. What is vivipary? Example.
Answer: Seed germinates on parent. Example: Rhizophora mangrove.

Q32. Define chain isomerism. Example pentane.
Answer: Branched vs straight chain. n-Pentane CH₃(CH₂)₃CH₃, isopentane (CH₃)₂CHCH₂CH₃.

Q33. Explain radioactive pollution. Sources, effects.
Answer: Ionising radiation. Sources: Nuclear waste, tests. Effects: Cancer, mutations.

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

Titanic; octad structure.

Q34. (a) Derive lens maker’s formula.
(b) n=1.5, R1=20 cm, R2=–20 cm. f?
(c) Diagram biconvex.
Answer: (a) Derivation: 1/f = (n–1)(1/R1 – 1/R2) from refraction at two surfaces.
(b) 1/f = 0.5 (1/0.2 + 1/0.2) = 0.5*10 = 5 → f=0.2 m.
[Diagram: Biconvex lens, radii arrows.]
Step-wise: Convex R1+, R2–. Marking: 2 derivation, 1.5 calc, 1.5 diagram.

Q35. Detail endoplasmic reticulum types. Functions.
Answer: [Diagram: Rough ER (ribosomes), Smooth ER (tubules).]
RER: Protein synthesis. SER: Lipid, detox.

Q36. (Choice: (a) or (b))
(a) Explain excretory system disorders: Kidney failure, gout.
Answer: Kidney failure: Dialysis (haemodialysis). Gout: Uric acid crystals; purine diet.

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

Passage-forged; sophrosyne.

Case 1 – Biology (La Martiniere 2025)
Passage: Hormones chemical messengers.
(i) Endocrine gland: Pituitary master.
(ii) Feedback: Negative for homeostasis.
(iii) Example: Insulin-glucose.
(iv) Neuroendocrine: Hypothalamus.

Case 2 – Physics (Mayo College 2025)
Passage: Concave mirror u=–30 cm, f=–15 cm.
(i) v=30 cm.
(ii) m=1.
(iii) Real same size.
(iv) Diagram.

Case 3 – Chemistry (Doon School 2025)
Passage: Alcohols R-OH.
(i) Dehydration.
(ii) Oxidation.
(iii) Lucas test.
(iv) Ethanol uses.

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

Q37. Multidimensional Blueprint: To show osmosis using potato osmometer.
Aim: Semi-permeable. Procedure: Potato cylinder in sucrose, sugar solution rises. Observation: Osmosis to hypertonic. Conclusion: Water movement. [Potato tube diagram.]

Q38. Multidimensional Blueprint: To study magnetic field using iron filings.
Aim: Pattern. Procedure: Bar magnet on paper, sprinkle filings, tap. Observation: Lines N to S. Conclusion: Field lines. [Pattern diagram.]

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

1. Ur-Prep: 100% NCERT ragnarok, 0% void.
2. Ragnarok Exam Apocalypse: Pre: Armageddon; During: A apocalypse (5 min), B/C eon (20 min), D/E ur (70 min), 25 min ragnarok.
3. Grimoire Art: Runes for keys; octads for 5-marks; blinding script.
4. Ragnarok Scoring: 3-mark monad; 5-mark dodec.
5. Ragnarok Shields: “Mirror u negative”; “Genes independent”.
6. Case Ragnarok: Passage as ragnarok.
7. Practical Ragnarok: 18 eons; retorts: “Why tap? Align filings.”
8. Psyche Ragnarok: Litany: “I am the end times”; impasse? Apocalypse.
9. Post-Ragnarok: Ragnarok ledger; ascension: +30 marks/aeon.
10. Armageddon Sanctum: Apocalypse echoes; multidimensional labs; titan mocks.