12th Chemistry top 20 Repeated Three Marks

1. Describe a method for refining Nickel. (3 times)
2. Describe the structure of diborane. (3 times)
3. Derive an expression for the Nernst equation. (3 times)
4. Write a note on Fischer-Tropsch synthesis. (2 times)
5. Explain Schottky defect. (2 times)
6. Distinguish between tetrahedral and octahedral voids. (2 times)
7. Write Reimer-Tiemann reaction. (2 times)
8. Explain the common ion effect with an example. (2 times)
9. Calculate the packing efficiency in FCC. (2 times)
10. Explain why [Ti(H₂O)₆]³⁺ is coloured while [Sc(H₂O)₆]³⁺ is colourless. (2 times)
11. State Faraday’s law of electrolysis. (2 times)
12. Write a note on Frenkel defect. (2 times)
13. What is Lanthanide contraction? (2 times)
14. Give the uses of helium. (2 times)
15. List the consequences of Lanthanide contraction. (2 times)
16. Write the mechanism of Aldol condensation. (2 times)
17. Write Clemmensen reduction. (2 times)
18. What is catenation? Write the conditions for catenation property. (2 times)
19. Why do d-block elements exhibit variable oxidation states? (2 times)
20. In an octahedral crystal field, draw and explain the splitting of d-orbitals. (2 times)
21. State Kohlrausch’s Law and explain one of its applications. (2 times)
22. Describe the adsorption theory of catalysis. (2 times)
23. Write the test for the carboxylic acid group. (2 times)
24. How are proteins classified based on their structure? Explain. (2 times)
25. Write the uses of silicones. (2 times)
26. What are antioxidants? (2 times)
27. Calculate the percentage efficiency of packing in a face-centered cubic crystal. (2 times)
28. Explain the postulates of Werner’s theory. (2 times)
29. Explain the optical and kinetic property of colloids. (2 times)
30. How will you convert phenol into the following compounds: Picric acid, Phenolphthalein. (2 times)
31. How is terylene prepared? (2 times)
32. Distinguish between order and molecularity of a reaction. (2 times)
33. The rate constant for a first-order reaction is 1.54 × 10⁻³ s⁻¹. Calculate its half-life. (2 times)
34. How will you prepare Potash Alum? (2 times)
35. What are interstitial compounds? Give its properties. (2 times)
36. What is a pseudo-first-order reaction? Give an example. (2 times)
37. Write any two chemical methods for the preparation of colloids. (2 times)
38. Mention the consequences of Lanthanide contraction. (2 times)
39. Write Bragg’s equation. (2 times)
40. Define Equivalent Conductance. Give its unit. (2 times)
41. How will you protect metals from corrosion? (2 times)
42. Write a short note on anomalous properties of the first element of the p-block. (2 times)
43. Gabriel phthalimide synthesis?
44. How is acrolein prepared?
45. Mustard oil reaction?
46. K₄[Mn(CN)₆] properties:
    (i) Central metal atom
    (ii) Oxidation state
    (iii) Co-ordination number
    (iv) Nature of ligand
    (v) Magnetic properties
47. Explain the concentration of ore by the Froth flotation process.
48. Differentiate Lanthanides and Actinides.
49. A zero-order reaction is 20% complete in 20 minutes. Calculate the value of the rate constant. In what time will the reaction be 80% complete?

Other Important Three Marks

1. Give the structure of CO₂. (SP² Hybridised is written as an annotation in the image.)
2. Identify the order for the following reactions:
   (i) Rusting of iron
   (ii) Radioactive disintegration of ⁹²U
   (iii) 2A + 3B → Product rate = k [A] [B]
3. Define Saytzeff’s rule.
4. Factors affecting electrolytic conductance. (Any 3 points)
5. H₂ – O₂ fuel cell?
6. [Ni(CN)₄]²⁻ is diamagnetic? Explain.
7. Ionisation isomers? Explain.
8. Explain the McAfee process.
9. What is the major product obtained when 2,3-dimethyl pentan-3-ol is heated in the presence of H₂SO₄?
10. Write the balanced equation for the reaction between Chlorine with cold NaOH and hot NaOH.
11. Explain Metal Excess Defect.
12. Distinguish between Rate and Rate Constant.
13. Write a short note on Trope nitrile condensation reaction.
14. Write the IUPAC names of the following:
    (i) [Cu(NH₃)₄]SO₄
    (ii) [FeF₆]⁴⁻
15. Elucidate the structure of glucose.
16. Calculate the concentration of OH⁻ in a fruit juice that contains 2 × 10⁻³ M H₃O⁺ ion. Identify the nature of the solution.
17. Mention the Anode, Cathode, Electrolyte, and Uses of Mercury button cell.
18. Explain the characteristics of a catalyst (any three points).
19. Explain gravity separation process.
20. List out the uses of oxygen.
21. Draw the figure to show the splitting of d-orbitals in an Octahedral field.
22. Write the Mechanism of Cannizzaro reaction.
23. Identify the enzyme catalyst in the following reactions:
    (i) Oxidation of ethanol into acetic acid
    (ii) Hydrolysis of starch into maltose
    (iii) Hydrolysis of urea
24. Describe the structure of fructose and write the test which identifies the presence of 6 carbon atoms in it.
25. Give one example for:
    (i) Tranquilizer
    (ii) Antihistamin
    (iii) Artificial sweetening agent
26. Discuss and explain galvanic cell notation with an example.
27. Explain the intermediate compound formation theory of catalysis.
28. What are the colours obtained by 1°, 2°, 3° alcohols in Victor Meyer’s test?
29. Explain the reduction of nitromethane in acid medium.