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12th Chemistry Practice paper-02

3 pages, 69 questions, 9 questions with responses, 9 total responses,

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CHEMISTRY Class II PreUni Plus 2016-2017 Practice Paper - 02 Max. Marks Duration Date 70 3 hours 01-02-2017 Instructions 1. The questions paper has four parts: A, B, C and D. All parts are compulsory. 2. Write balanced chemical equations and draw labeled diagrams wherever required. 3. Use log tables and the simple calculator if necessary (Use of scientific calculators is not allowed). PART - A I. Answer the following questions (one mark each) [10 1 = 10] 1. Out of 0.1 molal aqueous solutions of glucose and sodium chloride respectively. Which one will have high boiling point? 2. What is the significance of Henry s law constant, KH? 3. State Kohlrausch s law for independent migration of ions. 4. What must be the minimum energy required by the reactants to undergo chemical reaction? 5. How does adsorption of a gas on a solid vary with temperature? 6. What is the role of iodine in the refining of titanium? 7. Write the structure of XeF2. 8. Why is chloroform kept in coloured bottles? O 9. Given: CHO + C CH3 NaOH A. heat Identify the product A. 10. Name the nitrogenous base present in RNA but not in DNA. PART - B II. Answer any FIVE of the following questions (two marks each) [5 2 = 10] 11. Write two differences between Frenkel and Schottky defects. 12. Show that the half life period for a first order reaction is independent of the initial concentration of the reactants. 13. The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 Scm 1. Calculate its molar conductivity. 14. Name the element in the 3d series that (a) shows maximum oxidation states (b) is diamagnetic [1 + 1] 15. How is picric acid obtained from phenol? Write chemical equation for the reaction. 16. Explain Rosenmund s reduction with an example. 17. What are tranquilizers? Give an example for neurotransmitters. 18. Explain saponification with an example. 2P1617CPP2 1 PART - C III. Answer any FIVE of the following questions (three marks each) [5 3 = 15] 19. Write the chemical reactions which takes place during the following processes: (i) reduction of ferric oxide to iron when temperature is less than 1073 K. (ii) reduction of zinc oxide to zinc. (iii) Mond s process for refining of nickel. [1 + 1 + 1] 20. Describe contact process for the manufacture of sulphuric acid. 21. (a) How is phosphine prepared in the laboratory? [2] (b) Write the reaction for the thermal decomposition of sodium azide. [1] 22. Complete the following reactions: (a) 2NaOH + Cl2 (b) XX + H2O (c) XeF4 + SbF5 [1 + 1 + 1] 23. Give reason (one each) for the following: (a) Transition metals act as catalysts (b) Second ionisation enthalpy of copper is very high (c) The spin only magnetic moment of Sc3+ is zero (Z = 21) [1 + 1 + 1] 24. (a) Complete and balance the following ionic equations: (i) MnO 4 C 2O 42 H (ii) Cr2O72 2OH (b) Which lanthanoid ion acts as a good oxidising agent? [2 + 1] 25. (a) What are heteroleptic complexes? (b) Write the IUPAC name of K3[Cr(C2O4)3] (c) When is linkage isomerism possible in coordination compounds? 3+ [1 + 1 + 1] 3 26. (a) Explain why [Fe(H2O)6] has magnetic value of 5.92 BM whereas [Fe(CN)6] has a value of only 1.74 BM. (b) What is spectrochemical series? [2 + 1] PART - D IV. Answer any THREE of the following questions (five marks each) 27. (a) Calculate the packing efficiency of simple cubic crystal. [3 5 = 15] [2] (b) An element crystallizes in fcc lattice. If edge length of the unit cell is 408.6 pm and density is 10.5 g cm 3. Calculate the atomic mass of the element. [2] (c) What are ferromagnetic substances? [1] 28. (a) 200 cm3 of an aqueous solution of a protein contains 1.26 g of protein. The osmotic pressure of such a solution at 300 K is found to be 2.57 10 3 bar. Calculate the molar mass of the protein. [Given: R = 0.083 L bar mol 1 K 1] [3] (b) What are azeotropes? Mention the types of azeotropes. 2P1617CPP2 2 [2] 29. (a) Calculate the standard Gibb s free energy change and equilibrium constant for the cell reaction 2Fe3 (aq) 2I (aq) 2Fe2 (aq) I 2 (s) The emf of the cell is 0.236 V at 298 K. [Given: R = 8.314 J mol 1 K 1] [3] (b) Describe the construction and working of standard hydrogen electrode. [2] 30. (a) The first order rate constant of -elimination of ethyl iodide, C2H5I(g) C2H4(s) + HI(g) at 600 K is 1.6 10 5 s 1. Calculate the rate constant for the reaction at 700 K, if the activation energy of the reaction is 209 kJ mol 1. [Given: R = 8.314 J K 1 mol 1] [3] (b) Explain the influence of a catalyst on the rate of a reaction using energy profile diagram. 31. (a) Explain the mechanism of enzyme catalysis. [2] [2] (b) Write the Freundlich adsorption isotherm and explain the terms involved in the expression. [2] (c) State Hardy-Schulze rule. [2] V. Answer any FOUR of the following questions (five marks each) [4 5 = 20] 32. (a) Explain the stereochemical consequences of SN1 reaction by taking 2-bromobutane as an example.[3] (b) Write the reactions of haloarenes with (i) Sodium (ii) Magnesium 33. (a) Write the reaction of ethanol with (i) benzoic acid and conc.H2SO4 (ii) PCC (iii) Excess of conc.H2SO4 at 443 K [1 + 1] [1] [1] [1] (b) Explain Reimer-Tiemann reaction. [2] 34. (a) Explain cross aldol condensation reaction with an example. (b) Explain decarboxylation reaction with an example. (c) Complete the following equation : [2] [2] CH2 CH3 (i) KMnO4/KOH (ii) H3O+ 35. (a) How is benzene diazonium chloride prepared by diazotization? Write the relevant equation. [1] [2] (b) Explain the preparation of ethanamine by Gabriel phthalimide synthesis. [2] (c) Write the increasing order of basic strength of the following amines in aqueous solution: (C2H5)3N, C2H5NH2, (C2H5)2NH. [1] 36. (a) Write the Haworth s structure of -lactose. [2] (b) What are fibrous proteins? Give an example. [2] (c) Name the sugar present in DNA. [1] 37. (a) Write the classification of polymers on the basis of their structure. [2] (b) How is Nylon-2-nylon-6 prepared? [2] (c) Write the structure of monomer of natural rubber. [1] *** 2P1617CPP2 3

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