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CBSE Class 12 Board Exam 2016 : Chemistry (Series S)

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SET-1 Series ONS U . Code No. U . 56/1/S U U U- S - c U U Roll No. Candidates must write the Code on the title page of the answer-book. U - c U 16 - U U U U U- S - c U U U - 26 U M U , - 15 U - U q 10.15 10.15 10.30 U - U U - S U U Please check that this question paper contains 16 printed pages. Code number given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate. Please check that this question paper contains 26 questions. Please write down the Serial Number of the question before attempting it. 15 minute time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the students will read the question paper only and will not write any answer on the answer-book during this period. U ( h ) CHEMISTRY (Theory) 3 U Time allowed : 3 hours 70 U 56/1/S Maximum Marks : 70 1 P.T.O. (i) (ii) 1 5 - U U (iii) 6 10 - U U (iv) 11 22 - U U (v) 23 U U (vi) 24 26 - U U (vii) , U U U U 4 2 1 3 5 General Instructions : (i) All questions are compulsory. (ii) Questions number 1 to 5 are very short answer questions and carry 1 mark each. (iii) Questions number 6 to 10 are short answer questions and carry 2 marks each. (iv) Questions number 11 to 22 are also short answer questions and carry 3 marks each. (v) Question number 23 is a value based question and carry 4 marks. (vi) Questions number 24 to 26 are long answer questions and carry 5 marks each. (vii) Use log tables, if necessary. Use of calculators is not allowed. 56/1/S 2 1. CH25CH 2 CH2Cl U CH32CH22CH2Cl ? SN1 Out of CH25CH 2CH2Cl and CH32CH22CH2Cl, which is more reactive towards SN1 reaction ? 2. HNO3 U U U U U U U m U On heating Zn granules with conc. HNO3, a brown gas is evolved which undergoes dimerization on cooling. Identify the gas. 3. U U U U S U ? What type of magnetism is shown by a substance if its domains are arranged in equal number and in opposite directions ? 4. . . . . . Write the IUPAC name of the given compound : 56/1/S 3 P.T.O. 5. U S U U ? What is the reason for the stability of colloidal sols ? 6. U S U U , U , U U U (i) ? (ii) S ? (iii) U U U U ? (iv) ? For the given cells : Lead storage cell, Mercury cell, Fuel cell and Dry cell Answer the following : (i) Which cell is used in hearing aids ? (ii) Which cell was used in Apollo space programme ? (iii) Which cell is used in automobiles and inverters ? (iv) Which cell does not have long life ? 7. U U S MnO2 KOH S U (A) U (B) (i) (ii) (A) U (B) (B) ? When pyrolusite ore MnO2 is fused with KOH in presence of air, a green coloured compound (A) is obtained which undergoes disproportionation reaction in acidic medium to give a purple coloured compound (B) : (i) Write the formulae of the compounds (A) and (B). (ii) What happens when compound (B) is heated ? 56/1/S 4 8. PdCl2.4NH3 AgNO3 2 AgCl U (i) U (ii) . . . . . When a coordination compound PdCl2.4NH3 is mixed with AgNO3, 2 moles of AgCl are precipitated per mole of the compound. Write : 9. (i) Structural formula of the complex (ii) IUPAC name of the complex Pt 2NH3 (g) N 2 (g ) 13H2 (g ) U5k (i) U U (ii) k U Pt N g 13H g . For a reaction : 2NH3 (g) 2( ) 2( ) Rate5k 10. (i) Write the order and molecularity of this reaction. (ii) Write the unit of k. U U (i) (ii) - U S M U U (i) U U U (ii) U U 56/1/S 5 P.T.O. Write the chemical equations involved in the following reactions : (i) Clemmensen reduction (ii) Hell-Volhard Zelinsky reaction OR How do you convert 11. (i) Toluene to benzaldehyde (ii) Ethanoyl chloride to ethanal U f.c.c. S U 7g cm23 280 g U l ? 400 pm An element crystallizes in a f.c.c. lattice with cell edge of 400 pm. The density of the element is 7g cm23. How many atoms are present in 280 g of the element ? 12. H2O2 U U U S U U m U log k 5 14.2 2 1.0 3 10 4 K T Ea U U S U k U - 200 U ( R58.314 JK21 mol21) The rate constant for the first order decomposition of H2O2 is given by the following equation : log k 5 14.2 2 1.0 3 10 4 K T Calculate Ea for this reaction and rate constant k if its half - life period be 200 minutes. (Given : R58.314 JK21 mol21) 56/1/S 6 13. (i) U CaCl2 c U ? (ii) S U ? U (iii) U U U U U ? (i) Out of silica gel and anhydrous CaCl2, which will adsorb the water H2SO4 U H3PO4 vapours ? (ii) Out of H2SO 4 and H 3PO4, which one is more effective in causing coagulation of positively charged sol ? Give reason. (iii) Out of sulphur sol and proteins, which one forms macromolecular colloids ? 14. (i) Uc U (ii) h Al2O3 Al c Al2O3 NaOH U U h U U U ? (iii) U S U c U ? (i) Name the method of refining Zirconium. (ii) In the extraction of Al, impure Al2O3 is dissolved in conc. NaOH to form sodium aluminate and leaving impurities behind. What is the name of this process ? (iii) What is the function of limestone in the extraction of iron from its oxides ? 15. 298K U E0cell U 2Cr(s)13Fe21(0.01M) 2Cr31(0.01M)13Fe(s) : Ecell50.261 V 56/1/S 7 P.T.O. Calculate E0cell for the following reaction at 298K : 2Cr(s)13Fe21(0.01M) 2Cr31(0.01M) 13Fe(s) Given : Ecell50.261 V 16. U 17 U ( ) S U U 14 U S (i) Mn (ii) Zn (iii) Eu21 Cr U U U U Give reasons : (i) Mn shows the highest oxidation state of 17 with oxygen but with fluorine it shows the highest oxidation state of 14. (ii) Zn is soft whereas Cr is hard. (iii) Eu21 is a good reducing agent. 17. U U U U (i) 2, 4, 6 (ii) 2- U U (iii) U S KOH Na U U U U U U What happens when : (i) 2, 4, 6 - trinitrochlorobenzene is treated with warm water. (ii) 2-chlorobutane is treated with alcoholic KOH. (iii) ethyl chloride is treated with Na metal in presence of dry ether. Write the equation involved in the above reactions. 56/1/S 8 18. U (a) U (R-CO-R) U U (R-CHO) (b) U U U (c) U - U Give reasons for the following : 19. (a) Aldehydes (R-CHO) are more reactive than ketones (R-CO-R) towards nucleophilic addition reaction. (b) Benzaldehyde does not undergo aldol condensation reaction. (c) Benzoic acid does not give Friedal-Crafts reaction. (i) CH3COCl / pyridine Br2 / KOH C6 H5 2 COO2NH41 A B C (ii) CHCl3 1 alc. KOH NaNO2 / Cu Sn / HCl B C6 H5N 21BF42 A C Complete the following reactions : (i) CH3COCl / pyridine Br2 / KOH C6 H5 2 COO2NH41 A B C (ii) CHCl3 1 alc. KOH NaNO2 / Cu Sn / HCl B C6 H5N 21BF42 A C 56/1/S 9 P.T.O. 20. (i) U t - U U U ? (ii) (iii) S PVC, -6, -N U U U (i) What is the role of t-butyl peroxide in the polymerization of ethene ? (ii) Identify the monomers in the following polymer : (iii) Arrange the following polymers in the increasing order of their intermolecular forces : PVC, Nylon-6, Buna-N OR Write the mechanism of free radical polymerization of ethene. 56/1/S 10 21. (i) U U U U U (ii) U (iii) U U U U U U - U (i) Write the name of two monosaccharides obtained on hydrolysis of maltose sugar. (ii) Name the vitamin whose deficiency causes convulsions. (iii) Write one example each for Fibrous protein and Globular protein. 22. (a) [CoF6]32 U , U U S ( . . Co527) (b) [Co(en)2Cl2]1 U (a) For the complex [CoF6]32, write the hybridization, magnetic character and spin of the complex. (At. number : Co527) (b) 23. Draw one of the geometrical isomers of the complex [Co(en)2Cl2]1 which is optically active. S U . S U U U U U M U . S . U m U h U U U U . S U U U U U U U U U U (i) . U m U ( ) ? (ii) U U U ? (iii) U $ U ? U 56/1/S 11 P.T.O. Due to hectic and busy schedule, Mr. Awasthi made his life full of tensions and anxiety. He started taking sleeping pills to overcome the depression without consulting the doctor. Mr. Roy, a close friend of Mr. Awasthi, advised him to stop taking sleeping pills and suggested to change his lifestyle by doing Yoga, meditation and some physical exercise. Mr. Awasthi followed his friend s advice and after few days he started feeling better. After reading the above passage, answer the following : (i) What are the values (at least two) displayed by Mr. Roy ? (ii) Why it is not advisable to take sleeping pills without consulting doctor ? (iii) What are tanquilizers ? Give two examples. 24. (a) (b) U (i) H2S H2Te (ii) PCl3 PCl5 (iii) h (i) HClO4 (ii) XeOF4 U U (i) S H3PO3, H3PO4, H3PO2 U Xe U U ? (ii) He (iii) U U S ? (iv) U (v) SO2 56/1/S U ? 12 (a) Account for the following : (i) H2 Te is more acidic than H2S. (ii) PCl5 is more covalent than PCl3. (iii) Boiling points of interhalogens are little higher as compare to pure halogens. (b) Draw the structures of : (i) HClO4 (ii) XeOF4 OR (i) Arrange the following in the increasing order of their reducing character : H3PO3, (ii) H3PO4, H3PO2 Out of He and Xe, which one can easily form compound and why ? (iii) Write the conditions to maximize the yield of ammonia in Haber s process. (iv) Write two uses of Chlorine gas. (v) 25. (a) How can you detect the presence of SO2 gas ? (i) (ii) (iii) 56/1/S 13 P.T.O. (b) - Conc.H2SO4 / 413K 2CH3CH2OH CH3CH2 2 O2 CH2CH3 (a) U (i) (ii) (iii) HI (b) (a) NaOH CS2 S U U (i) U U U (ii) U t- U Write the product(s) in each of the following reactions : (i) (ii) (iii) (b) Write the mechanism of the following reaction : Conc.H2SO4 / 413K 2CH3CH2OH CH3CH2 2 O2 CH2CH3 56/1/S 14 OR (a) Write equations of the following reactions : (i) Bromine in CS2 with phenol (ii) Treating phenol with chloroform in the presence of aq.NaOH (iii) Anisole reacts with HI (b) 26. (a) Distinguish between : (i) Ethanol and Diethyl ether (ii) Propanol and t-butyl alcohol U 50 g Na2SO4 (M5142 g mol21) 2 g U Na2SO4 (Kb 50.52 K kg mol21) (b) U (i) U (ii) U (a) CS2 100 g 2.56 g U 0.383 K U (Sx) U (Kf CS2 53.83 K kg mol21 U . 532 g mol21) (b) 56/1/S U U U U U U ? 0.9% (i) 1.2% U U U (ii) 0.4% U U U 15 P.T.O. (a) Calculate the boiling point of solution when 2 g of Na 2 SO 4 (M5142 g mol21) was dissolved in 50 g of water, assuming Na2SO4 undergoes complete ionization. (Kb for water50.52 K kg mol21) (b) Define the following terms : (i) Colligative properties (ii) Ideal solution OR (a) When 2.56 g of sulphur was dissolved in 100 g of CS2, the freezing point lowered by 0.383 K. Calculate the formula of sulphur (Sx). (Kf for CS253.83 K kg mol21 Atomic mass of Sulphur532 g mol21) (b) 56/1/S Blood cells are isotonic with 0.9% sodium chloride solution. What happens if we place blood cells in a solution containing ? (i) 1.2% sodium chloride solution (ii) 0.4% sodium chloride solution 16

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