II PUC MODEL QUESTION PAPER 2026
CHEMISTRY (Subject Code: 34)
Maximum Marks: 70 Time: 3 Hours 15 Minutes
(15 minutes for reading the question paper)
Instructions:
1. The question paper has five parts. All parts are compulsory.
2. Write the serial number of the question before attempting it.
3. Figures in the margin indicate full marks.
4. Use log tables and simple calculator if necessary (use of scientific calculator is not allowed).
5. Part-A carries 20 marks.
1. The question paper has five parts. All parts are compulsory.
2. Write the serial number of the question before attempting it.
3. Figures in the margin indicate full marks.
4. Use log tables and simple calculator if necessary (use of scientific calculator is not allowed).
5. Part-A carries 20 marks.
PART - A
I. Select the correct option from the given choices. Each question carries 1 mark. (15 × 1 = 15)
1. Which of the following is not a characteristic of p-type semiconductor?
2. The van't Hoff factor for dilute solution of K₂SO₄ in water is close to:
3. In the reaction of oxalate with permanganate in acidic medium, the number of electrons involved in producing one molecule of CO₂ is:
4. The rate of a reaction doubles when the temperature is raised from 293 K to 303 K. The activation energy of the reaction is:
5. Which of the following is an example of multimolecular colloid?
6. The magnetic moment of [NiCl₄]²⁻ is:
7. Which of the following statements is correct regarding the reaction: 2HI(g) ⇌ H₂(g) + I₂(g)?
8. The order of basic strength of amines in gaseous phase is:
9. The most stable oxidation state of lanthanoids is:
10. The IUPAC name of CH₃-CH(OH)-CH=CH₂ is:
11. In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with:
12. The functional group present in R-COOR' is:
13. Which of the following biomolecules is not a polymer?
14. The monomer of nylon-6,6 is:
15. Which of the following is an antiseptic?
II. Fill in the blanks by choosing the appropriate word from the brackets. (5 × 1 = 5)
16. The unit of rate constant for a zero-order reaction is (mol L⁻¹ s⁻¹ / s⁻¹ / mol⁻¹ L s⁻¹).
17. is the process of conversion of a colloidal solution to suspension (Flocculation / Coagulation / Peptization).
18. The hybridization of the carbon atom in CH₃⁺ is (sp³ / sp² / sp).
19. is the reducing sugar (Fructose / Sucrose / Starch / Cellulose).
20. The drug used to relieve pain and inflammation is (Antihistamine / Tranquilizer / Analgesic / Antibiotic).
PART - B
Answer any FIVE questions. Each question carries TWO marks. (5 × 2 = 10)
21. Define Schottky defect. Give one example.
22. State Henry's law. Write its mathematical expression.
23. What is corrosion? Mention one method to prevent it.
24. Explain the term 'activation energy' of a reaction.
25. Draw the structure of XeF₄ and predict its shape.
26. Write the chemical equation for the preparation of ethene from ethanol.
27. How is iodoform prepared from ethanol?
28. What are zwitterions? Give an example.
PART - C
Answer any FIVE questions. Each question carries THREE marks. (5 × 3 = 15)
29. Explain the terms 'molarity' and 'molality' with examples.
30. Derive the integrated rate equation for a first-order reaction.
31. Describe the role of depressant in the froth flotation process.
32. Write short notes on: (a) Lanthanoid contraction (b) Actinoid contraction.
33. Explain the mechanism of SN¹ reaction with an example.
34. How are the following conversions carried out?
(a) Ethanol → ethanal
(b) Propanone → propene
(a) Ethanol → ethanal
(b) Propanone → propene
35. What are enzymes? Mention their classification based on composition.
PART - D
Answer any THREE questions. Each question carries FIVE marks. (3 × 5 = 15)
36. (a) State and explain Kohlrausch's law of independent migration of ions.
(b) The resistance of a conductivity cell filled with 0.1 M KCl solution is 100 Ω. If the resistance of the same cell when filled with 0.02 M KCl solution is 520 Ω, calculate the conductivity of 0.02 M KCl solution.
(Specific conductance of 0.1 M KCl = 1.29 × 10⁻² S cm⁻¹)
(b) The resistance of a conductivity cell filled with 0.1 M KCl solution is 100 Ω. If the resistance of the same cell when filled with 0.02 M KCl solution is 520 Ω, calculate the conductivity of 0.02 M KCl solution.
(Specific conductance of 0.1 M KCl = 1.29 × 10⁻² S cm⁻¹)
37. (a) Explain the factors affecting the rate of a chemical reaction.
(b) The rate constant of a reaction is 2 × 10⁻² L mol⁻¹ s⁻¹ at 25°C. What will be the rate constant if the reaction is zero order?
(b) The rate constant of a reaction is 2 × 10⁻² L mol⁻¹ s⁻¹ at 25°C. What will be the rate constant if the reaction is zero order?
38. Describe the preparation of potassium dichromate from chromite ore. Write the chemical equations involved.
39. (a) Explain the bonding in coordination compounds using valence bond theory. Take [CoF₆]³⁻ as an example.
(b) Write the IUPAC name of [Cr(en)₂Cl₂]⁺.
(b) Write the IUPAC name of [Cr(en)₂Cl₂]⁺.
40. Explain the reactions of aldehydes and ketones with:
(a) HCN (b) NaBH₄ (c) Tollen's reagent.
(a) HCN (b) NaBH₄ (c) Tollen's reagent.
PART - E
Answer any THREE questions. Each question carries THREE marks. (3 × 3 = 9)
(All workings must be shown)
41. Calculate the packing efficiency of a simple cubic lattice.
42. A solution contains 10 g of urea (molar mass 60 g/mol) dissolved in 200 g of water. Calculate the freezing point of the solution if Kf for water is 1.86 K kg mol⁻¹.
43. For the reaction 2A + B → C, the rate = k[A]²[B]. If the concentration of A is doubled and B is halved, what will be the change in rate?
44. The half-life of a first-order reaction is 30 minutes. What is the rate constant?
45. Calculate the cell potential for the cell:
Zn | Zn²⁺ (0.1 M) || Cu²⁺ (0.01 M) | Cu
Given E°Zn = –0.76 V, E°Cu = +0.34 V.
Zn | Zn²⁺ (0.1 M) || Cu²⁺ (0.01 M) | Cu
Given E°Zn = –0.76 V, E°Cu = +0.34 V.
46. The rate of diffusion of a gas is 12 mL/s. If the rate of diffusion of SO₂ is 6 mL/s, find the molecular mass of the gas.
Note: This model paper is prepared strictly according to the latest Karnataka PUC blueprint and previous year question paper pattern (2025). For official updates, visit the Department of Pre-University Education website.
DETAILED ANSWER KEY WITH FULL EXPLANATIONS
1. (c) p-type has lower conductivity than n-type due to lower mobility of holes.
2. (c) K₂SO₄ → 2K⁺ + SO₄²⁻ → i = 3 (ideal dilute solution)
3. (a) C₂O₄²⁻ → 2CO₂ + 2e⁻ → 1 CO₂ requires 1 e⁻
4. (b) log(k₂/k₁) = Ea/2.303R (1/T₁ – 1/T₂)
log 2 = Ea/(19.15) × (10/303×293)
Ea = 2 × 19.15 × (10/303×293) × 2.303 × 8.314 × 10³ ≈ 53.6 kJ/mol
Ea = 2 × 19.15 × (10/303×293) × 2.303 × 8.314 × 10³ ≈ 53.6 kJ/mol
5. (a) Sulphur sol → S₈ molecules → multimolecular
6. (c) [NiCl₄]²⁻ → sp³, 2 unpaired e⁻ → √8 = 2.82 BM
7. (a) Decomposition of HI is endothermic (ΔH = +ve)
8. (b) Gas phase: no solvation → 3° > 2° > 1° > NH₃
9. (b) +3 due to poor shielding of f-electrons
10. (a) CH₃-CH(OH)-CH=CH₂ → longest chain 4C, OH at 2, double bond at 3 → But-3-en-2-ol
11. (a) 2Cu₂O + Cu₂S → 6Cu + SO₂ (self-reduction)
12. (b) Ester: R-COO-R'
13. (c) Glycine is amino acid monomer, others are polymers
14. (a) Nylon-6,6 → adipic acid + hexamethylenediamine
15. (b) Chloroxylenol → dettol component → antiseptic
16. mol L⁻¹ s⁻¹ [Rate] = mol L⁻¹ s⁻¹ → k has same unit for zero order
17. Coagulation Colloid → suspension by electrolyte
18. sp² CH₃⁺ → planar, empty p-orbital
19. Fructose Ketose → reducing sugar
20. Analgesic Pain reliever → aspirin, paracetamol
21. Schottky defect: Equal number of cations and anions missing → lowers density.
Example: NaCl, KCl, CsCl
Example: NaCl, KCl, CsCl
22. Henry's law: Solubility of gas ∝ partial pressure
p = KH × x or S = KH × p
23. Corrosion: Electrochemical rusting of iron
Method: Galvanization (Zn coating) or cathodic protection
Method: Galvanization (Zn coating) or cathodic protection
24. Minimum extra energy needed by reactant molecules to form products.
Ea = Energy of activated complex – Energy of reactants
Ea = Energy of activated complex – Energy of reactants
25. XeF₄ → 6 electron pairs (4 bond + 2 lone) → octahedral → square planar
F F
\ /
Xe --- F --- F
/ \
F F
(lone pairs above & below)26.
CH₃CH₂OH →[Conc. H₂SO₄, 443K] CH₂=CH₂ + H₂O
27. Iodoform reaction:
CH₃CH₂OH + 4I₂ + 6NaOH → CHI₃↓ + HCOONa + 5NaI + 5H₂O
28. Zwitterion: Amino acid at isoelectric point → ⁺H₃N–CH(R)–COO⁻
Example: Glycine ⁺H₃N–CH₂–COO⁻
Example: Glycine ⁺H₃N–CH₂–COO⁻
29.
Molarity (M) = moles of solute / volume in litres
Ex: 5.85 g NaCl in 500 mL → 0.2 M
Molality (m) = moles / kg of solvent
Ex: 5.85 g NaCl in 500 g water → 0.2 m
Molarity (M) = moles of solute / volume in litres
Ex: 5.85 g NaCl in 500 mL → 0.2 M
Molality (m) = moles / kg of solvent
Ex: 5.85 g NaCl in 500 g water → 0.2 m
30. For first order: Rate = k[A]
d[A]/dt = –k[A] → ∫ d[A]/[A] = –k ∫ dt
ln[A₀]/[A] = kt → k = 2.303/t log[A₀]/[A]
ln[A₀]/[A] = kt → k = 2.303/t log[A₀]/[A]
31. Depressant (NaCN) in froth flotation:
→ Forms complex with ZnS → prevents it from coming into froth
→ Allows PbS/Galena to float
→ Forms complex with ZnS → prevents it from coming into froth
→ Allows PbS/Galena to float
32.
(a) Lanthanoid contraction: Poor shielding of 4f electrons → steady decrease in size from La to Lu
(b) Actinoid contraction: Even stronger due to poorer 5f shielding
(a) Lanthanoid contraction: Poor shielding of 4f electrons → steady decrease in size from La to Lu
(b) Actinoid contraction: Even stronger due to poorer 5f shielding
33. SN¹ → unimolecular → rate = k[RX]
Step 1: Slow → R⁺ + X⁻ (carbocation)
Step 2: Fast → R⁺ + Nu⁻ → R–Nu
Example: (CH₃)₃C–Br + H₂O → (CH₃)₃C–OH + HBr → racemisation
Step 1: Slow → R⁺ + X⁻ (carbocation)
Step 2: Fast → R⁺ + Nu⁻ → R–Nu
Example: (CH₃)₃C–Br + H₂O → (CH₃)₃C–OH + HBr → racemisation
34.
(a) CH₃CH₂OH →[PCC] CH₃CHO
(b) CH₃COCH₃ →[N₂H₄/KOH] CH₃CH₂CH₃ (Wolf-Kishner)
(a) CH₃CH₂OH →[PCC] CH₃CHO
(b) CH₃COCH₃ →[N₂H₄/KOH] CH₃CH₂CH₃ (Wolf-Kishner)
35. Enzymes: Biological catalysts (proteins)
Classification:
1. Pure protein (pepsin)
2. Conjugated (protein + non-protein cofactor)
Classification:
1. Pure protein (pepsin)
2. Conjugated (protein + non-protein cofactor)
36. (a) Kohlrausch’s law: Λ°m = ν⁺ λ°⁺ + ν⁻ λ°⁻
(b) Cell constant = κ × R = 1.29 × 10⁻² × 100 = 1.29 cm⁻¹
For 0.02 M: κ = 1.29 / 520 = 2.48 × 10⁻³ S cm⁻¹
(b) Cell constant = κ × R = 1.29 × 10⁻² × 100 = 1.29 cm⁻¹
For 0.02 M: κ = 1.29 / 520 = 2.48 × 10⁻³ S cm⁻¹
37. (b) Given k = 2 × 10⁻² L mol⁻¹ s⁻¹ → second order
Zero order unit → mol L⁻¹ s⁻¹ → cannot be same
Zero order unit → mol L⁻¹ s⁻¹ → cannot be same
38.
1. 4FeCr₂O₄ + 8Na₂CO₃ + 7O₂ → 8Na₂CrO₄ + 2Fe₂O₃ + 8CO₂
2. 2Na₂CrO₄ + H₂SO₄ → Na₂Cr₂O₇ + Na₂SO₄ + H₂O
3. Na₂Cr₂O₇ + 2KCl → K₂Cr₂O₇ + 2NaCl
1. 4FeCr₂O₄ + 8Na₂CO₃ + 7O₂ → 8Na₂CrO₄ + 2Fe₂O₃ + 8CO₂
2. 2Na₂CrO₄ + H₂SO₄ → Na₂Cr₂O₇ + Na₂SO₄ + H₂O
3. Na₂Cr₂O₇ + 2KCl → K₂Cr₂O₇ + 2NaCl
39. (b) Dichloridobis(ethane-1,2-diamine)chromium(III) ion
40.
(a) HCN → cyanohydrin
(b) NaBH₄ → 1°/2° alcohol
(c) Tollen’s → RCHO + [Ag(NH₃)₂]⁺ → RCOOH + Ag↓ (silver mirror)
(a) HCN → cyanohydrin
(b) NaBH₄ → 1°/2° alcohol
(c) Tollen’s → RCHO + [Ag(NH₃)₂]⁺ → RCOOH + Ag↓ (silver mirror)
41. Simple cubic: a = 2r → volume = a³
Atoms per unit cell = 1
Volume of atoms = 4/3 π r³
Packing efficiency = (4/3 π r³ / (2r)³) × 100 = 52.4%
Atoms per unit cell = 1
Volume of atoms = 4/3 π r³
Packing efficiency = (4/3 π r³ / (2r)³) × 100 = 52.4%
42. ΔTf = i × Kf × m
m = 10/60 / 0.2 = 0.833 m
ΔTf = 1 × 1.86 × 0.833 = 1.55 K
Freezing point = 0 – 1.55 = –1.55°C
m = 10/60 / 0.2 = 0.833 m
ΔTf = 1 × 1.86 × 0.833 = 1.55 K
Freezing point = 0 – 1.55 = –1.55°C
43. Rate = k[A]²[B]
New rate = k(2A)²(B/2) = k × 4A² × B/2 = 2 × original rate → increases 2 times
New rate = k(2A)²(B/2) = k × 4A² × B/2 = 2 × original rate → increases 2 times
44. t½ = 0.693/k → k = 0.693/30 = 0.0231 min⁻¹
45. E = E° – 0.059/n log Q
E = 1.10 – 0.059/2 log(0.1/0.01) = 1.10 – 0.0295 × 1 = 1.0705 V ≈ 1.07 V
E = 1.10 – 0.059/2 log(0.1/0.01) = 1.10 – 0.0295 × 1 = 1.0705 V ≈ 1.07 V
46. r₁/r₂ = √(M₂/M₁)
12/6 = √(64/M) → 4 = 64/M → M = 16 g/mol → CH₄
12/6 = √(64/M) → 4 = 64/M → M = 16 g/mol → CH₄
ALL ANSWERS AS PER KARNATAKA PUC 2026 MARKING SCHEME
Use this for self-evaluation & board exam practice!