Punjab Board Class 12 Chemistry Model Paper 2026

PUNJAB SCHOOL EDUCATION BOARD

CLASS : 12th (Senior Secondary) | Code No. 2230

Series : SS/Annual Exam. – 2026 | SET : A

Subject : CHEMISTRY [ English Medium ]

ACADEMIC/OPEN (Only for Fresh/Re-appear/Improvement/Additional Candidates)

Time allowed : 3 hours Maximum Marks : 70

• Please make sure that the printed pages in this question paper are 16 in number and it contains 35 questions.
• The Code No. and Set on the right side of the question paper should be written by the candidate on the front page of the answer-book.
• Before beginning to answer a question, its Serial Number must be written.
• Don’t leave blank page/pages in your answer-book.
• Except answer-book, no extra sheet will be given. Write to the point and do not strike the written answer.
• All questions are compulsory.
• Section – A contains questions numbers 1 to 18 objective type questions (MCQ, Assertion-Reason, Fill in blanks). Each carries 1 mark.
• Section – B contains questions numbers 19 to 25 very short answer type questions. Each carries 2 marks.
• Section – C contains questions numbers 26 to 30 short answer type questions. Each carries 3 marks.
• Section – D contains questions 31 & 32 case-based questions. Each carries 4 marks.
• Section – E contains questions 33 to 35 long answer type questions. Each carries 5 marks.
• Internal choice is available in two questions of Section-B, C and all questions of Section-E.

SECTION – A (Objective Type Questions)

1. The rate of a reaction doubles when its temperature changes from 27°C to 37°C. The activation energy is:

(a) 53.6 kJ/mol (b) 26.8 kJ/mol (c) 13.4 kJ/mol (d) 107.2 kJ/mol

[1]

2. Which of the following is a pseudo first-order reaction?

(a) Inversion of cane sugar (b) Decomposition of H₂O₂ (c) Hydrolysis of ethyl acetate (d) Both (a) and (c)

[1]

3. Assertion (A): For a zero-order reaction, the rate is independent of concentration.
Reason (R): The rate law is rate = k [A]⁰.

(a) Both A and R are true and R is correct explanation of A. (b) Both A and R are true but R is not correct explanation. (c) A is true but R is false. (d) A is false but R is true.

[1]

4. The unit of rate constant for a reaction of order 3/2 is:

(a) L² mol⁻² s⁻¹ (b) L¹/² mol⁻¹/² s⁻¹ (c) L⁻¹/² mol¹/² s⁻¹ (d) mol L⁻¹ s⁻¹

[1]

5. In Freundlich adsorption isotherm, the value of 1/n is:

(a) Between 0 and 1 (b) Between 1 and 2 (c) Greater than 2 (d) Negative

[1]

6. Which of the following is an example of lyophobic colloid?

(a) Gelatin (b) Gum (c) Gold sol (d) Starch

[1]

7. The protecting power of lyophilic colloid is due to:

(a) Charge on particles (b) Large size (c) Solvation (d) None

[1]

8. Fill in the blank: The half-life of a first-order reaction is __________ of initial concentration.
[1]

9. Fill in the blank: In a face-centered cubic unit cell, the number of atoms per unit cell is __________.
[1]

10. The coordination number in hcp structure is __________.
[1]

11. Schottky defect is observed in crystals having __________ coordination number.
[1]

12. The SI unit of conductivity is __________.
[1]

13. The emf of a Daniel cell at 298 K is 1.1 V. When external voltage slightly greater than 1.1 V is applied, the cell behaves as __________.
[1]

14. The standard reduction potential of Cu²⁺/Cu is __________ V.
[1]

15. Kohlrausch’s law is used to determine __________.
[1]

16. The monomer of Teflon is __________.
[1]

17. Which of the following is a tranquilizer?

(a) Aspirin (b) Equanil (c) Penicillin (d) Paracetamol

[1]

18. The IUPAC name of CH₃CH₂CH(CH₃)COOH is __________.
[1]

SECTION – B (Very Short Answer Type Questions)

19. Define order of a reaction. Give one example of zero-order reaction.
[2]

20. What is meant by ‘collision frequency’? How does it affect the rate of reaction?
[2]

21. Explain the term ‘peptization’ with example.
[2]

OR What is Hardy-Schulz rule?

22. Calculate the packing efficiency in bcc lattice.
[2]

23. Why do transition metals exhibit variable oxidation states?
[2]

24. Write the IUPAC name and structure of K₃[CrF₆].
[2]

OR What is lanthanoid contraction?

25. Define ambidentate ligand. Give two examples.
[2]

SECTION – C (Short Answer Type Questions)

26. The rate constant for a first-order reaction is 6.93 × 10⁻³ s⁻¹. Calculate the time required for 75% completion of the reaction.
[3]

27. Explain the mechanism of cleansing action of soaps.
[3]

28. (i) What is meant by ‘forbidden zone’ in solids?
(ii) Give one example each of n-type and p-type semiconductor.
[3]

29. Write the chemical equations for the preparation of KMnO₄ from MnO₂.
[3]

OR Why is KMnO₄ purple in colour?

30. Explain the following terms with suitable examples:
(i) Cationic detergents
(ii) Anionic detergents
[3]

SECTION – D (Case-Based Questions)

Case Study – 1: A first-order reaction takes 69.3 minutes for 50% completion. The rate constant at 27°C is 1 × 10⁻² min⁻¹.

31. (a) What is the half-life period of the reaction?
[1]

(b) Calculate the time required for 75% completion.
[1]

(c) What is the activation energy if rate constant at 47°C is 2 × 10⁻² min⁻¹?
[2]

Case Study – 2: In a crystal of NaCl, one Na⁺ ion is missing and the vacancy is filled by an electron to maintain electrical neutrality. This defect is known as metal excess defect.

32. (a) Name the defect.
[1]

(b) How does it affect the density of the crystal?
[1]

(c) Give one example of a compound showing this defect.
[1]

(d) What is the colour imparted to the crystal?
[1]

SECTION – E (Long Answer Type Questions)

33. (a) Derive the integrated rate equation for a first-order reaction.
(b) A first-order reaction is 50% complete in 30 minutes at 27°C and in 10 minutes at 47°C. Calculate the activation energy.
[5]

OR Explain the factors affecting the rate of a chemical reaction with suitable examples.

34. (a) Explain the structure of [Co(NH₃)₆]³⁺ using valence bond theory.
(b) Why do transition metals form coloured compounds?
(c) What is meant by ‘stability constant’ of a complex?
[5]

OR Write the IUPAC names of the following:
(i) K₄[Fe(CN)₆]
(ii) [Co(en)₃]Cl₃
(iii) [Ni(CO)₄]

35. (a) What are biodegradable and non-biodegradable polymers? Give one example of each.
(b) Write the monomers of Nylon-6 and Buna-S.
(c) What is vulcanization of rubber?
[5]

OR Explain the preparation of Bakelite. Write its uses.

Marking Scheme Summary

Section	Questions	Marks per Question	Total
A	1–18	1 × 18	18
B	19–25	2 × 7	14
C	26–30	3 × 5	15
D	31–32	4 × 2	8
E	33–35	5 × 3	15
Grand Total			70

Download pdf PSEB Chemistry Sample Paper 2026

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Model Paper prepared based on PSEB previous year questions (PYQs) pattern | For practice only. Visit official website for latest notification.