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12th Chemistry Practice paper-03

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CHEMISTRY Class II PreUni Plus 2016-2017 Practice Paper - 03 Max. Marks Duration Date 70 3 hours 15 minutes 15-02-2017 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. Define molal depression constant. 2. What is the molality of aqueous NaCl solution if it boils at 100.104 C? [Given: Kb for H2O = 0.52 K kg mol 1] 3. Between Cu2+ and Ag+, which ion is reduced at the cathode? [Given: E oCu 2 /Cu 0.34 V, E oAg /Ag 0.80 V] 4. Draw the graph for rate of reaction v/s molar concentration of the reactant of a zero order reaction. 5. What is the cause for Brownian movement? 6. Which is the reducing agent during the extraction of iron from haematite? 7. Mention the noble gas element used in cancer therapy. 8. Which one of the alkyl halides has higher boiling point CH3I, C2H5I, C3H7I? 9. Complete the following reaction: (i) dry ether ____ RMgX 1 Alcohol Mg(X)OH (ii) H O/H 2 10. Give an example for reducing disaccharide. PART - B II. Answer any FIVE of the following questions (two marks each) [5 2 = 10] 11. LiCl acquires pink colour when heated in Li vapours. Give reason. 12. What happens to the molar conductivity of strong and weak electrolytes with dilution? Why? 13. Write two differences between order and molecularity of a reaction. 14. Why d-block elements (a) exhibit variable oxidation states (b) form coloured compounds 15. Between phenol and alcohol, which one is more acidic? Why? 2P1617CPP3 1 16. Given: CH3 CH3 C O N 2H 4 A KOH/glycol B + N2 H 2O Write the structures and names of A and B. 17. Why are detergents preferred over soaps? 18. What are antiseptics? Give an example. PART - C III. Answer any FIVE of the following questions (three marks each) [5 3 = 15] 19. How is blister copper extracted from copper matte by bessemerisation? 20. Arrange HClO4, HClO3 HClO2, HClO in the order of (i) Decreasing acidic strength (ii) Increasing oxidising power. Give reason 21. Describe the manufacture ammonia by Haber s process. 22. (a) Write the order of thermal stability of hydrides of group 16 elements. (b) Write an example for a reaction in which sulphuric acid act as a dehydrating agent. (c) Which element in group 16 is radioactive in nature? [1 + 1 + 1] 23. Explain the variation of atomic size is 3d series elements. 24. How is potassium permanganate manufactured? Write the equations. 3 25. Using VBT, explain the geometry and magnetic behaviour of Co NH3 6 . [Given: atomic no. of cobalt = 27] 26. (a) Explain linkage isomerism with example. (b) Write the IUPAC name of Na2[CrF4O]. [2 + 1] PART - D IV. Answer any THREE of the following questions (five marks each) [3 5 = 15] 27. (a) Calculate the packing efficiency in hexagonal close packing arrangement. (b) In corundum, oxide ions are arranged in hexagonal close packing and aluminium ions occupy twothird of the octahedral voids. What is the formula of corundum? [3 + 2] 28. Urea forms an ideal solution in water. Determine the vapour pressure of an aqueous solution containing 10 % by mass of urea at 40 C (Given: Vapour pressure of H2O at 40 C = 55.3 mm Hg; Molecular mass of urea = 60) [3 + 2] 29. (a) Calculate the equilibrium constant of the reaction of 298 K 2 o Mg (s) 2Ag aq Mg aq 2Ag (s) ;E cell 3.16V (b) Write the symbolic representation of standard hydrogen electrode and also its standard potential. [3 + 2] 30. (a) Derive an integrated rate equation for the rate constant of a first order reaction. (b) The time taken for 75 % completion of a first order reaction is 50 min. Calculate the rate constant of the reaction. [3 + 2] 2P1617CPP3 2 31. (a) Explain peptisation with a suitable example. (b) What are catalytic promoters? Give an example. (c) Write one example for shape selective catalysts. [2 + 2 + 1] V. Answer any FOUR of the following questions (five marks each) [4 5 = 20] 32. (a) Explain SN1 mechanism with an example. (b) Complete the reaction: Cl + 2 Na + Cl-CH3 + . Write the name of the reaction [3 + 2] 33. (a) Name the major product formed when the vapours of the following alcohols are passed over hot copper at 573 K: (i) Isopropyl alcohol (ii) Benzyl alcohol (b) Explain the mechanism of dehydration of ethanol. [2 + 3] 34. (a) Explain iodoform reaction with an example. (b) Explain the relative reactivity of aldehydes and ketones towards nucleophilic addition reactions. [2 + 3] 35. (a) Complete the following reactions: (i) CH3 CONH2 + Br2 + 4KOH (ii) C6H5 NH2 + CH3 COCl (iii) CH3 NH CH3 + C6H5SO2Cl (b) Write the IUPAC name of H (i) CH3 N C CH3 (ii) C6H5 N CH3 C2 H 5 CH3 CH3 [3 + 2] 36. (a) Write the Haworth structure of sucrose. (b) What is denaturation of proteins? Write an example. (c) How many peptide linkages are present in a pentapeptide? [2 + 2 + 1] 37. (a) Give an example for addition polymer. (b) How are polymers classified based on molecular forces? Give one example for each type. *** 2P1617CPP3 3 [1 + 4]

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