BISE Lahore — 10th Class Chemistry — Annual 2025 — Group I — Question Paper

English medium. Objective: 12 MCQs, 12 marks, 15 minutes. Subjective: 48 marks, 1 hour 45 minutes — Part-I: Q.2, Q.3, Q.4 (attempt any 5 of 8 short questions each, 10 marks each); Part-II: attempt any TWO of Q.5, Q.6, Q.7 (each has parts (a) 5 marks and (b) 4 marks).

Question stems below are transcribed from the board paper scans. The full MCQ option sets are as printed on the board paper itself (see the scan sources in sources.md); the answer key with reasons is in solutions.md.

Objective (Q.1 — 12 MCQs)

Q.1. In an irreversible reaction, dynamic equilibrium:

Q.2. Which one of the following is a Lewis base:

Q.3. K₄[Fe(CN)₆] is a:

Q.4. Which salt is used for manufacture of explosives, plastics and other chemicals:

Q.5. Anthracite contains the carbon content:

Q.6. Substitution reaction is the characteristics of:

Q.7. Which one of the following vitamins is water soluble:

Q.8. A good example of reducing sugar is:

Q.9. Which one of these pollutants is not found in car exhaust fumes:

Q.10. Which one of the following gases is used to destroy harmful bacteria in water:

Q.11. The type of hepatitis which can be caused by contaminated water is:

Q.12. Which one of the following is not fraction of residual oil:

Subjective — Part-I (short questions)

Q.2

(i) Write two macroscopic characteristics of forward reaction.

(ii) Write the equilibrium constant expression for the reaction: 2SO₂ + O₂ ⇌ 2SO₃

(iii) Define chemical equilibrium state.

(iv) Write any two physical properties of acid.

(v) Write reaction of acid with sulphides (Give equation).

(vi) Write formula of sodium hydroxide and potassium hydroxide.

(vii) How are alkyl halides reduced?

(viii) Define hydrocarbons. Give an example.

Q.3

(i) Why and how carbon completes its octet?

(ii) Define destructive distillation.

(iii) What is an ester group? Write down the formula of ethyl acetate.

(iv) Write down the general formula of lipids.

(v) Write the names of two fatty acids with their formulae.

(vi) Define pollutants and contaminants.

(vii) How is the temperature of atmosphere maintained?

(viii) Write the health problems created by SO₂.

Q.4

(i) Water dissolves sugar and alcohol, justify it.

(ii) Define soft water and hard water.

(iii) What is meant by leaching process?

(iv) Why are the non-polar compounds insoluble in water?

(v) How NaHCO₃ is converted to Na₂CO₃?

(vi) Describe froth flotation process.

(vii) How is roasting carried out in extraction of metal?

(viii) How is ammonia prepared for the manufacture of urea?

Q.5(a) Define salts. Explain preparation of soluble salts. (5)

Q.5(b) Differentiate between homocyclic and alicyclic compounds. (4)

Q.6(a) Give five uses of ethylene. (5)

Q.6(b) Explain the sources and uses of protein. (4)

Q.7(a) Define refining of petroleum and explain fractional distillation of petroleum. (5)

Q.7(b) Give four effects of acid rain. (4)

_Note: Q.5, Q.6, Q.7 long-question prompts appear above under their part headings. This file lists every question in the paper; no question has been added or removed._

Sources — BISE Lahore 10th Chemistry Annual 2025 — Group I

Paper scans (provenance)

• Objective scan: https://www.ilmkidunya.com/past_papers/past-paper-2025-lahore-board-class-10th-chemistry-group-i-objective-english-medium-117029.aspx
• Subjective scan: https://www.ilmkidunya.com/past_papers/past-paper-2025-lahore-board-class-10th-chemistry-group-i-subjective-english-medium-117030.aspx
• Source site: ilmkidunya.com individual paper pages (authentic board paper scans).
• Source checked: 2026-10-24 (transcription verified against the downloaded scan images; RapidOCR draft cross-checked and corrected from the images).
• Scan files (local staging copies, for verification only): chemistry-2025-gi-objective.jpg (2,587,643 bytes, sha256 prefix 58fad22ded7d8ab5), chemistry-2025-gi-subjective.jpg (2,508,930 bytes, sha256 prefix dfa1f15b4ca49479). No byte-duplicate with any other catalogue scan (checked against all 36 downloaded scans).

Textbook

• Punjab Textbook Board (PTB), Class 10 Chemistry (Chapters 9–16; official PCTB copy via PCTB Google Drive, file verified as the 2012-edition book, Ch. 9 Chemical Equilibrium onward).
• Key references used in review: Ch. 9 (macroscopic characteristics of forward/reverse reactions; chemical equilibrium state; Kc); Ch. 10 (acids; salts table incl. sodium chlorate use; preparation of soluble salts); Ch. 11 (organic chemistry; homocyclic vs alicyclic; destructive distillation; alkyl halide reduction Zn/HCl); Ch. 12 (hydrocarbons; ethylene uses; residual-oil fractions: lubricants, paraffin wax, asphalt, petroleum coke; refining/fractional distillation); Ch. 13 (biochemistry; triglyceride general formula; fatty acids; proteins); Ch. 14 (pollutants vs contaminants; greenhouse effect; SO₂ effects); Ch. 15 (water; chlorine; hepatitis E; leaching); Ch. 16 (chemical industries; froth flotation; roasting; urea/Haber).

Review notes

• Every question in this paper was legible on the scans; no question is published on a guess. Objective option sets were read from the scan image (not from OCR alone).
• Q.4 note: in the scan, the 'a' of "Na" prints low in the first option row, so options (A) and (B) read like "N₂ClO₃" and "N₂SiO₃". The intended compounds are NaClO₃ (sodium chlorate) and Na₂SiO₃ (sodium silicate) per the textbook's salts table, and the answer follows the table's use-match. This is recorded here, not hidden.
• Q.8 note: maltose is also a reducing sugar; glucose is the textbook's named example and the expected board answer. Recorded in solutions.md, not hidden.
• No numerical-calculation questions appear in this paper. The single derived expression (Q.2(ii) Kc) was derived twice independently with agreement; the two-pass checklist item is marked done on that basis, and this note is the log.
• Pattern verified against the scan header: Objective 12 marks / 15 minutes; Subjective 48 marks / 1 hour 45 minutes; Part-I 10 marks per question (Q.2, Q.3, Q.4); Part-II (a) 5 marks, (b) 4 marks (Q.5, Q.6, Q.7). Total 60.

Caveat

None. All items in this group are fully verified against the textbook and scans.