II PUC Chemistry Model Solved Paper 2026

GOVERNEMENT OF KARNATAKA
KARNATAKA SCHOOL EXAMINATION AND ASSEMENT BOARD
6th CROSS, MALLESHWARAM, BENGALURU-560003
2025-26 II PUC MODEL QUESTION PAPER-1

Subject: 34 - Chemistry Maximum Marks: 70

Time: 3.00 Hours Number of Questions: 46

Instructions

1. Question paper has FIVE parts. All parts are compulsory.
2. a. Part-A carries 20 marks. Each question carries 1 mark.
b. Part-B carries 06 marks. Each question carries 2 marks.
c. Part-C carries 15 marks. Each question carries 3 marks.
d. Part-D carries 20marks. Each question carries 5 marks.
e. Part-E carries 09 marks. Each question carries 3 marks.
3. In Part-A questions, first attempted answer will be considered for awarding marks.
4. Write balanced chemical equations and draw neat labeled diagrams and graphs wherever necessary.
5. Direct answers to the numerical problems without detailed steps and specific unit for final answer will not carry any marks.
6. Use log tables and simple calculator if necessary (use of scientific calculator is not allowed).
7. For a question having circuit diagram/figure/ graph/ diagram, alternate questions are given at the end of question paper in a separate section for visually challenged students.

PART-A

I. Select the correct option from the given choices. Each question carries 1 mark.

1. The mass percentage (W/W) of glucose in water is 10% means:

• (a) 10g of glucose dissolved in 100 g of water
• (b) 10g of glucose dissolved in 90 mL of water
• (c) 10g of glucose dissolved in 100 mL of water
• (d) 10g of glucose dissolved in 90 g of water

Answer: (d) 10g of glucose dissolved in 90 g of water

2. Which of the following elements is liquid at normal temperature?

• (a) Zinc
• (b) Mercury
• (c) Aluminum
• (d) Water

Answer: (b) Mercury

3. The reagent used in Sandmeyer's reaction is:

• (a) N₂ gas
• (b) Cu and HCl
• (c) Cu₂Cl₂ and HCl
• (d) CuCl₂

Answer: (c) Cu₂Cl₂ and HCl

4. The main natural source of acetic acid is:

• (a) milk
• (b) vinegar
• (c) red ant
• (d) butter

Answer: (b) vinegar

5. The reaction of aniline, which produces Zwitter ion as a major product is:

• (a) direct nitration
• (b) bromination
• (c) sulphonation
• (d) Friedel-craft alkylation

Answer: (c) sulphonation

6. The method used to separation of isomeric products obtained when phenol reacts with dil. HNO₃ at low temperature is:

• (a) steam distillation
• (b) sublimation
• (c) electrolysis
• (d) solidification

Answer: (a) steam distillation

7. The ligand which forms more stable coordination complexes is:

• (a) NH₃
• (a) C₂O₄²⁻
• (a) CN₋
• (a) H₂O

Answer: (c) CN⁻

8. Which of the following groups when present at para position increases the basic strength of aniline?

• (a) -NO₂
  
• (b) -Br
• (c) -NH₂
• (d) -COOH

Answer: (c) -NH₂

9. In the following acids, vitamin is:

• (a) ascorbic acid
• (b) adipic acid
• (c) aspartic acid
• (d) saccharic acid

Answer: (a) ascorbic acid

10. The best reagent useful for separation and purification of aldehyde from ketone is:

• (a) Tollens' reagent
• (b) sodium hydrogen sulphite
• (c) sodium sulphate
• (d) 2,4-DNP reagent

Answer: (b) sodium hydrogen sulphite

11. Statement-1: If on mixing the two liquids, the solution becomes hot, it implies that it shows negative deviation from Raoult's law.
Statement-2: Solutions which show negative deviation are accompanied by decrease in volume.

• (a) Both Statement–1 and Statement–2 are true.
• (b) Statement–1 is true but Statement–2 is false;
• (c) Both Statement–1 and Statement–2 are false.
• (d) Statement–1 is false but Statement–2 is true.

Answer: (a) Both Statement-1 and Statement-2 are true.

12. Match the following transition metal/compounds with their catalytic activity in the corresponding processes.

Transition metal/compounds	Name of the process
(i) TiCl4 + Al(CH3)3	(A) Wacker process
(ii) PdCl2	(B) Contact process
(iii) Ni	(C) manufacture of polyethene
(iv) V2O5	(D) hydrogenation of fat

• (a) i-C, ii-A, iii-D, iv-B
• (b) i-C, ii-A, iii-D, iv-B
• (c) i-A, ii-C, iii-D, iv-B
• (d) i-D, ii-A, iii-B, iv-C

Answer: (a) i-C, ii-A, iii-D, iv-B

13. Cumene hydroperoxide on hydrolysis of dilute acids gives:

• (a) phenol and oxygen
• (b) phenol and hydrogen
• (c) hydrogen and oxygen
• (d) phenol and acetone

Answer: (d) phenol and acetone

14. Among the following cells, the cell used in the Apollo space program for providing electric power is:

• (a) SHE
• (b) H₂O₂ fuel cell
• (c) Daniel cell
• (d) Mercury cell

Answer: (b) H₂-O₂ fuel cell

15. The following results have been obtained during kinetic studies of the reaction A_(aq) + 2B_(aq) ⎯⎯→ C_(aq). Choose the correct option for the rate equation for the above reaction.

Experiment	Concentration of [A] (molL−1)	Concentration of [B] (molL−1)	Rate of formation of 'C' (molL−1)min−1
I	0.1	0.1	6.0x102−
II	0.2	0.3	7.2x102−
III	0.1	0.4	2.4x102−
IV	0.4	0.3	2.88x101−

Based on kinetic studies (Exp I & III: [B] x4, Rate x4; Exp II & IV: [A] x2, Rate x4), choose the correct rate equation:

Answer: (c) Rate = K[A]²[B]¹

II. Fill in the blanks

16. The polyhalo compound used as an aesthetic during surgery was:

Answer: chloroform

17. Nucleic acids are the long chain polymers of:

Answer: nucleotide

18. Van't Hoff factor for KCl solution assuming the complete dissociation is:

Answer: two

19. The number of hydroxyl groups present in glycerol is:

Answer: three

20. Formation of interstitial compounds makes the transition metal more:

Answer: hard

PART-B

III. Answer any three of the following. Each question carries 2 marks.

21. What is Lucas reagent? Which class of alcohol does produces turbidity immediately with it?

• Lucas Reagent: It is a mixture of concentrated hydrochloric acid (HCl) and anhydrous zinc chloride (ZnCl₂).
• Alcohol Class: Tertiary alcohols produce turbidity immediately at room temperature.

22. Write the S_N2 mechanism for conversion of chloromethane to methanol.

The S_N2 mechanism is a bimolecular nucleophilic substitution that occurs in a single step via a transition state:

Must Read S_N2 mechanism

• The nucleophile (OH⁻) attacks the carbon atom from the backside, opposite to the leaving group (Cl⁻).
• A transition state is formed where the C—OH bond is partially forming and the C—Cl bond is partially breaking.
• The reaction results in the inversion of configuration.

23. For the reaction: H₂(g) + I₂(g) → 2HI(g); draw the diagram showing plot of potential energy versus reaction coordinate to explain the role of activated complex in a reaction.

Activated Complex: It is the unstable intermediate formed at the peak of the potential energy curve. Once the activated complex is formed, it can either break apart to reform the reactants or proceed forward to form the products (2HI), depending on the direction of molecular vibration and energy distribution.

24. Name the hormone released rapidly due to rise in blood glucose level to keep the blood glucose level within the narrow limit. Mention the number of amino acids present in this hormone.

• Hormone Name: Insulin.
• Number of Amino Acids: It contains 51 amino acids.

25. What are transition elements? Give an example.

• Definition: Transition elements are defined as those which have incompletely filled d-orbitals in their ground state or in any of their common oxidation states.
• Example: Iron (Fe) or Copper (Cu).

PART-C

IV. Answer any three of the following. Each question carries 3 marks.

26. Using Valence Bond Theory [VBT] explain geometry, hybridisation and magnetic property of [CoF₆]^3- ion. [Given: Atomic number of cobalt is 27]

• Oxidation state: In [CoF₆]^3-, Cobalt is in +3 oxidation state (Co³⁺: [Ar] 3d⁶).
• Hybridisation: Since F^- is a weak field ligand, it does not cause pairing of electrons. It uses outer 4d orbitals, resulting in sp³d² hybridisation.
• Geometry: The geometry of the complex is Octahedral.
• Magnetic property: It has four unpaired electrons, making it Paramagnetic (High spin complex).

27. Heteroleptic complexes with co-ordination number 6 show geometrical isomerism. A complex [MA₃B₃] shows geometrical isomerism. Predict the denticity and draw the structure of two geometrical isomers of the complex and name them.

• Denticity: The ligands A and B are Unidentate (monodentate).
• Isomers: The two geometrical isomers are Facial (fac) and Meridional (mer).

28. What is Lanthanoid contraction? Mention two consequence of it.

• Definition: The steady decrease in the atomic and ionic radii of lanthanoid elements with increasing atomic number is called lanthanoid contraction.
• Consequences:
  1. Similarity in the properties of second (4d) and third (5d) transition series (e.g., Zr and Hf have almost identical radii).
  2. Difficulty in the separation of lanthanoids due to similar chemical properties.

29. How many square pyramidal units present in decacarbonyldimanganese(0)? Write its molecular and structural formulae.

• Units: There are two square pyramidal units joined by a Mn—Mn bond.
• Molecular Formula: Mn₂(CO)₁₀

30. Complete the following equations.

• (a) 4 FeCr₂O₄ + 8 Na₂CO₃ + 7 O₂ → 8 Na₂CrO₄ + 2 Fe₂O₃ + 8 CO₂
• (b) MnO₂ fused with KOH and oxidized with air gives K₂MnO₄ (Potassium manganate).
• (c) 2KMnO₄ → K₂MnO₄ + MnO₂ + O₂

V. Answer any two of the following. Each question carries 3 marks.

31. Mention three factors that affect the rate of a chemical reaction.

1. Concentration of reactants.
2. Temperature.
3. Presence of a catalysis.

32. Name the concentration term which is commonly used in medicine and pharmacy. Write the definition and mathematical equation for that concentration term.

• Concentration Term: Mass percentage (w/w) or Mass by volume percentage (w/v).
• Definition (Mass by volume %): It is the mass of solute dissolved in 100 mL of the solution.
• Mathematical Equation:
  Mass by volume percentage = (Mass of solute / Volume of solution in mL) × 100.

33. Depending on the magnitude of conductivity of the materials, mention the three types of materials with an example.

• Conductors: Materials with very high conductivity, e.g., Metals like Copper or Silver.
• Insulators: Materials with very low conductivity, e.g., Glass or Ceramics.
• Semiconductors: Materials with conductivity between conductors and insulators, e.g., Silicon or Germanium.

34. The diagram shows that when iron is exposed to atmospheric air:

• a) Name the phenomenon involved in this diagram.
• b) write the atmospheric oxidation reaction of iron.
• c) mention any one method to avoid this phenomenon.

• a) Name of phenomenon: Corrosion (or specifically, Rusting of iron).
• b) Atmospheric oxidation reaction:
  Anode: 2Fe(s) → 2Fe²⁺ + 4e⁻.
  Cathode: O₂(g) + 4H⁺(aq) + 4e⁻ → 2H₂O(l).
  Overall: 2Fe(s) + O₂(g) + 4H⁺(aq) → 2Fe²⁺(aq) + 2H₂O(l).
• c) Method to avoid: Painting the surface, galvanization, or using anti-rust solutions.

Karnataka 2nd PUC Chemistry Solved Paper 2026