Tamil Nadu Class 11 Chemistry Model Question Paper 1 — Samacheer Kalvi Plus One

Instructions

• Total Marks: 70
• Time: 3 hours
• Part A: 15 × 1 = 15 marks
• Part B: 5 × 3 = 15 marks (attempt any 5 from 8)
• Part C: 4 × 10 = 40 marks (attempt any 4 from 6, with internal choice)

Part A — One Mark Questions (MCQ / Fill in the blank)

1. The number of moles in 22 g of CO₂ is ____. (a) 0.5 (b) 1 (c) 2 (d) 0.25 2. The quantum number that defines the shape of an orbital is ____. (a) n (b) l (c) mₗ (d) mₛ 3. Across a period, atomic radius ____. (a) increases (b) decreases (c) remains same (d) fluctuates 4. Which gas law gives PV = constant? (a) Charles' (b) Gay-Lussac's (c) Boyle's (d) Avogadro's 5. ΔG < 0 for a process indicates it is ____. (a) non-spontaneous (b) at equilibrium (c) spontaneous (d) endothermic 6. The van't Hoff factor for CaCl₂ is ____. (a) 1 (b) 2 (c) 3 (d) 4 7. Which of the following has the highest electronegativity? (a) O (b) N (c) F (d) Cl 8. IUPAC name of CH₃COCH₂CH₃ is ____. (a) butanone (b) butan-2-one (c) butanal (d) butanoic acid 9. Bond order in N₂ is ____. (a) 1 (b) 2 (c) 3 (d) 2.5 10. Which type of hydride is NaH? (a) covalent (b) metallic (c) ionic (d) none 11. pH of 0.001 M HCl is ____. (a) 1 (b) 2 (c) 3 (d) 4 12. Boyle's law is applicable at constant ____. (a) pressure (b) temperature (c) volume (d) moles 13. The hybridisation in BF₃ is ____. (a) sp (b) sp² (c) sp³ (d) sp³d 14. Mesomeric +M effect is shown by ____. (a) –NO₂ (b) –CHO (c) –OH (d) –COOH 15. Which of the following is a colligative property? (a) viscosity (b) osmotic pressure (c) refractive index (d) surface tension

Part B — Three Mark Questions (answer any 5)

1. State and explain Hund's rule of maximum multiplicity with the example of oxygen (Z = 8). 2. Calculate the pH of a 0.1 M solution of acetic acid (Ka = 1.8 × 10⁻⁵). 3. A gas at STP occupies 5.6 L. Find the number of moles and number of molecules. 4. Explain the inductive effect with –I and +I examples. How does –I effect increase acidity? 5. What are geometric isomers? Draw and name the cis-trans isomers of 2-butene. 6. Distinguish between Kp and Kc. Derive the relation Kp = Kc(RT)^Δng. 7. Why does the boiling point of H₂O (100°C) far exceed that of H₂S (−60°C)? 8. State Le Chatelier's principle. Apply it to the industrial synthesis of ammonia.

Part C — Five Mark Questions (answer any 4 with internal choice)

1. (a) Describe the Solvay process for the manufacture of Na₂CO₃ with all equations. OR (b) Explain the mole concept. Calculate the number of molecules in 49 g of H₂SO₄.

2. (a) Explain Gibbs free energy. Derive ΔG = ΔH − TΔS. State all four cases of spontaneity. OR (b) State Hess's law. Given: H₂ + ½O₂ → H₂O, ΔH = −286 kJ; C + O₂ → CO₂, ΔH = −394 kJ; C₂H₂ + 5/2O₂ → 2CO₂ + H₂O, ΔH = −1300 kJ. Calculate ΔHf of C₂H₂.

3. (a) Explain VSEPR theory with the examples of CH₄, NH₃, H₂O, and PCl₅. OR (b) Draw the MO energy level diagram for O₂. Calculate bond order and state magnetic character.

4. (a) Explain all four colligative properties with their formulae and practical importance. OR (b) Derive the expression for osmotic pressure π = CRT. What is the van't Hoff factor? Give examples of association and dissociation.

Answer Hints

Part A: 1-a, 2-b, 3-b, 4-c, 5-c, 6-c, 7-c, 8-b, 9-c, 10-c, 11-c, 12-b, 13-b, 14-c, 15-b

Part B key points:

• Q2: [H⁺] = √(Ka × C) = √(1.8 × 10⁻⁵ × 0.1) = 1.34 × 10⁻³; pH = 2.87
• Q3: n = 5.6/22.4 = 0.25 mol; N = 0.25 × 6.022 × 10²³ = 1.505 × 10²³