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12th Chemistry Practice paper-04

3 pages, 63 questions, 14 questions with responses, 14 total responses,

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CHEMISTRY Class II PreUni Plus 2016-2017 Practice Paper - 04 Take Home Max. Marks Duration 70 3 hours 15 minutes 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. Under what condition van t Hoff factor i is less than one? 2. How is Henry s law constant (KH) related to the solubility of a gas? 3. What is the quantity of electricity required to liberate 1 mole of O2 gas from water? 4. What is the effect of temperature on half life period of a first order reaction? 5. Which one of the following has higher flocculation value for a negatively charged colloid: NaCl, MgCl2, AlCl3? 6. Why coke is not used as a reducing agent for Cr2O3? 7. What prompted Neil Bartlett to prepare Xe[PtF6]? 8. Solubility of haloalkanes in water is very low although they are polar in nature. Give reason. 9. How many moles of alcohol are required to convert one mole of an aldehyde into acetal? 10. Write the structure of -amino acid below isoelectric point. PART - B II. Answer any FIVE of the following questions (two marks each) [5 2 = 10] 11. What is Schottky defect? Give an example of a compound which possesses both Schottky and Frenkel defect. 12. State Kohlrausch s law. Write the equation for the calculation of of Ba(OH)2 using suitable strong electrolytes. 13. Explain with an example why rate of a reaction does not change when some reactions are carried out on the surface of a substance. Mention the order of the reaction. 14. Name the element in the 3d series (a) which contains maximum number of unpaired electrons (b) which is colourless in +2 oxidation state [1 + 1] 15. Explain the preparation of tertiary alcohol from Grignard reagent. 2P1617CPP4 1 16. Give reasons: (a) Acetophenone does not give addition product with NaHSO3. (b) Formic acid gives positive result with Tollen s reagent. 17. What are barbiturates? To which class of drugs do they belong? 18. What is the use of ranitidine? PART - C III. Answer any FIVE of the following questions (three marks each) [5 3 = 15] 19. (a) Describe van Arkel process for the extraction of zirconium. (b) Write the composition of copper matte. [2 + 1] 20. (a) Write chemical reactions which indicate that all the P Cl bonds in PCl5 molecule are not equivalent. (b) Draw the structure of H3PO3. (c) Why NO2 dimerises to form N2O4? [1 + 1 + 1] 21. Explain the manufacture of sulphuric acid from purified SO2. 22. (a) Write the reactions in which fluorine exhibits anomalous behaviour. (b) Interhalogens are more reactive than halogens. Give reason. [1 + 1] 23. (a) Between [Sc(H2O)6]3+ and [Ti(H2O)6]3+ ions, which is coloured and why? Give reason. (b) Vanadium pentoxide act as a catalyst. Give reason. [2 + 1] 24. (a) Complete the following: (i) 2MnO 4 16H 5C 2 O 42 (ii) 2Mn 2 [1] 8H 2 O SO 2 [1] (b) Between La(OH)3 and Lu(OH)3, which one is more basic and why? 25. Using VBT, explain the geometry and magetic property of [NiCl4]2 . [Given: Atomic No. of Ni = 28] 26. (a) Explain the crystal field splitting of d-orbital in an octahedral complex. (b) Give an example for hexadentate ligand. [2 + 1] PART - D IV. Answer any THREE of the following questions (five marks each) [3 5 = 15] 27. (a) CsCl has bcc arrangement and its unit cell edge length is 400 pm. Calculate the density of the crystal. [Given: At. Mass of Cs = 133 and Cl = 35.5] (b) What are ferromagnetic substances? Write an example. [3 + 2] 28. (a) A solution prepared by dissolving 1.25 g of oil of winter green (methyl salicylate) in 99.0 g of benzene has a boiling point of 80.31 C. Determine the molar mass of the compound. (Given: B.P. of pure benzene = 80.10 C and Kb for benzene = 2.53 C kg mol 1) (b) State Raoults Law of binary liquid mixture. 2P1617CPP4 [3 + 2] 2 29. (a) Write the cell representation of the following reaction: Mg(s) 2Ag (0.0001 M) Mg 2 (0.130 M) 2Ag(s) Calculate Ecell [Given: E Mg2 /Mg 2.37 V and E Ag /Ag 0.8 V ] (b) Rusting is an electrochemical process. Explain. [3 + 2] 30. (a) Explain the effect of catalyst on rate of a reaction. (b) Show that t87.5% = 3t50% of a first order reaction. [3 + 2] 31. (a) What are micelles? Explain the mechanism of micelle formation. (b) Write two differences between physisorption and chemisorption. V. Answer any FOUR of the following questions (five marks each) [3 + 2] [4 5 = 20] 32. (a) Explain SN2 mechanism of methyl chloride to methyl alcohol. (b) Mention the major product formed in the following reactions. (i) C 2 H 5 Cl Ag CN ....... AgCl (alc) anhyd. (ii) C6 H5 Cl CH 3Cl ....... HCl AlCl3 (c) Why is it necessary to avoid even traces of moisture while using Grignard reagent? [2 + 2 + 1] 33. (a) Explain Reimer-Tiemann reaction. (b) Complete the following equations: CH 3 Cl C2 H5 ONa and write the name of the reaction. [3 + 2] 34. (a) Explain Gattermann Koch reaction. (b) Explain the relative reactivity of propanone, acetaldehyde and formaldehyde towards nucleophilic addition reactions. [2 + 3] 35. (a) What is Hinsberg reagent? How is it used to distinguish a primary amine from a secondary amine? (b) Complete the following: OH .. (i) N N (ii) N N Cl + Cl OH Cu2Cl2 / HCl [1+2+2] 36. (a) What are disaccharides? Give an example. (b) Show that aminoacids are amphoteric in nature. (c) Name the components present in nucleic acids. [2 + 2 + 1] 37. (a) How are polymers classified based on the method of preparation? (b) What is vulcanisation? Name the monomer present in natural rubber. (c) Write an example for biodegradable polymer. [2 + 2 + 1] *** 2P1617CPP4 3

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