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

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SET-1 Series ONS U . Code No. U . 56/1/C 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) U 3 U 70 Time allowed : 3 hours 56/1/C Maximum Marks : 70 1 P.T.O. (i) (ii) 1 (iii) 6 10 - U U (iv) 11 (v) 23 (vi) 24 (vii) , U U U U 5 - U U 2 26 4 22 - U U U U 1 3 - U U 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/C 2 1. C4H9Br U SN1 1 Write the structure of an isomer of compound C4H9Br which is most reactive towards SN1 reaction. 2. Pb(NO3)2 U U U U U U U U m U 1 Pb(NO3)2 on heating gives a brown gas which undergoes dimerization on cooling ? Identify the gas. 3. U U U U 1 Give an example each of a molecular solid and an ionic solid. 4. . . . . . 1 Write the IUPAC name of the given compound : 5. U S U U ? 1 What is the reason for the stability of colloidal sols ? 56/1/C 3 P.T.O. 6. 7. (i) U (A) (B) KH ( U S U ) U U ? (ii) U , U ? (i) Gas (A) is more soluble in water than Gas (B) at the same temperature. Which one of the two gases will have the higher value of KH (Henry s constant) and why ? (ii) In non-ideal solution, what type of deviation shows the formation of maximum boiling azeotropes ? U (i) (ii) BrF3 2 XeF4 (i) Fe31 (ii) XeF4 U SbF5 SO2 ? ? Write the structures of the following : (i) BrF3 (ii) XeF4 OR What happens when : (i) SO2 gas is passed through an aqueous solution Fe31 salt ? (ii) XeF4 reacts with SbF5 ? 56/1/C 2 4 8. CoCl3.6NH3 AgNO3 AgCl (i) U (ii) . . . . . 2 When a coordination compound CoCl3.6NH3 is mixed with AgNO3, 3 moles of AgCl are precipitated per mole of the compound. Write 9. (i) Structural formula of the complex (ii) IUPAC name of the complex hv H2 1 Cl 2 2HCl 2 U5k (i) U U (ii) k U hv For a reaction : H2 1 Cl 2 2HCl Rate5k (i) Write the order and molecularity of this reaction. (ii) Write the unit of k. 56/1/C 5 P.T.O. 10. U U (i) - U (ii) 2 Write the chemical equations involved in the following reactions : (i) Hoffmann-bromamide degradation reaction (ii) Carbylamine reaction U b.c.c. c U 7.5g cm23 300 g U ? 11. 500pm 3 An element crystallizes in a b.c.c. lattice with cell edge of 500pm. The density of the element is 7.5g cm23. How many atoms are present in 300 g of the element ? 12. U c U C2H5Cl(g) C2H4(g) 1 HCl(g) Time/sec U U /atm 0 0.30 300 0.50 U S U U ( log 250.301, log 350.4771, log 450.6021) For the first order thermal decomposition reaction, the following data were obtained : C2H5Cl(g) C2H4(g) 1 HCl(g) Time / sec Total pressure / atm 0 0.30 300 0.50 Calculate the rate constant (Given : log 250.301, log 350.4771, log 450.6021) 56/1/C 6 3 13. U (i) U (ii) U (iii) U 3 Define the following terms : (i) Lyophilic colloid (ii) Zeta potential (iii) Associated colloids 14. (i) Uc U 3 (ii) c U ? (iii) U U U c U ? (i) Name the method of refining of nickel (ii) What is the role of cryolite in the extraction of aluminium ? (iii) What is the role of limestone in the extraction of iron from its oxides ? 15. MgSO4 (M5120 g mol21) 4 g 100 g U , U MgSO4 U (Kb 3 50.52 K kg mol21) Calculate the boiling point of solution when 4 g of MgSO4 (M5120 g mol21) was dissolved in 100 g of water, assuming MgSO4 undergoes complete ionization. (Kb for water50.52 K kg mol21) 56/1/C 7 P.T.O. 16. U 3 TeO2 (i) SO2 (ii) U U U (iii) I2 ICl Give reasons : (i) SO2 is reducing while TeO2 is an oxidizing agent. (ii) Nitrogen does not form pentahalide. (iii) ICl is more reactive than I2. 17. (a) (b) (c) 56/1/C (i) CHCl 1 aq.NaOH H (ii) 3 C6H52OH 1 8 3 Write the final product (s) in each of the following reactions : (a) (b) (c) 18. (i) CHCl 1 aq.NaOH H (ii) 3 C6H52OH 1 U 3 (i) U - U (ii) (iii) U U U U (CH3)3 N (CH3)2 NH U Give reasons for the following : (i) Aniline does not undergo Friedal-Crafts reaction. (ii) (CH3)2 NH is more basic than (CH3)3 N in an aqueous solution. (iii) Primary amines have higher boiling point than tertiary amines. 56/1/C 9 P.T.O. 19. M U U (i) U (ii) 1- U (iii) 2- U U-2- 3 (i) (ii) (iii) How do you convert : (i) Chlorobenzene to biphenyl (ii) Propene to 1-iodopropane (iii) 2-bromobutane to but-2-ene OR Write the major product(s) in the following : (i) (ii) (iii) 56/1/C 10 20. (i) U U U U ? (ii) (iii) U U S 3 U U , , (i) What is the role of Sulphur in the vulcanization of rubber ? (ii) Identify the monomers in the following polymer : (iii) Arrange the following polymers in the increasing order of their intermolecular forces : Terylene, Polythene, Neoprene 21. (i) S U U U U (ii) U ? (iii) U U U U U U U (i) Write the structural difference between starch and cellulose. (ii) What type of linkage is present in Nucleic acids ? 3 (iii) Give one example each for fibrous protein and globular protein. 56/1/C 11 P.T.O. [Fe(H2O)6]31 U , U U S ( . . Fe526) [Pt(en)2Cl2]21 c 3 S U U U U U M U U U U . . U U U UU U . U U . U U U U U U U . U U U U U U U (i) . ( ) ? (ii) U U ? U (iii) U U ? U 4 22. (a) (b) (a) (b) 23. For the complex [Fe(H 2O)6 ]31, write the hybridization, magnetic character and spin of the complex. (At. number : Fe526) Draw one of the geometrical isomers of the complex [Pt(en)2Cl2]21 which is optically inactive. Due to hectic and busy schedule, Mr. Singh started taking junk food in the lunch break and slowly became habitual of eating food irregularly to excel in his field. One day during meeting he felt severe chest pain and fell down. Mr. Khanna, a close friend of Mr. Singh. took him to doctor immediately. The doctor diagnosed that Mr. Singh was suffering from acidity and prescribed some medicines. Mr. Khanna advised him to eat home made food and change his lifestyle by doing yoga, meditation and some physical exercise. Mr. Singh 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. Khanna ? (ii) What are antacids ? Give one example. (iii) Would it be advisable to take antacids for a long period of time ? Give reason. 56/1/C 12 24. (a) 298K U E8cell U 5 2Al(s)1 3Cu21(0.01M) 2Al31 (0.01M) 1 3Cu(s) (b) : Ecell 5 1.98 V A U B E8 U U U ? [E8(Fe21/Fe)520.44V] E8(A21/A)522.37V : E8 (B21/B)520.14V (a) 0.001 mol L21 3.90531025 S cm21 U U U U (a) U CH3COOH l0 (H1)5349.6 S cm2 mol21 U l0 (CH3COO2)540.9 S cm2 mol21 (b) l U U l U E8cell s U ? (a) Calculate E8cell for the following reaction at 298K : 2Al(s)1 3Cu21(0.01M) 2Al31 (0.01M) 1 3Cu(s) Given : Ecell 5 1.98 V (b) Using the E8 values of A and B, predict which is better for coating the surface of iron [E8(Fe21/Fe)520.44V] to prevent corrosion and why ? Given : E8(A21/A)522.37V : E8 (B21/B)520.14V OR (a) The conductivity of 0.001 mol L 21 solution of CH 3 COOH is 3.90531025 S cm21. Calculate its molar conductivity and degree of dissociation (a). Given l0 (H1)5349.6 S cm2 mol21 and l0 (CH3COO2)540.9 S cm2 mol21 (b) 56/1/C Define electrochemical cell. What happens if external potential applied becomes greater than E8cell of electrochemical cell ? 13 P.T.O. U 25. (a) 5 (i) Mn S 17 U S 14 (ii) Cr21 (iii) Cu21 U Zn21 U (b) (i) (ii) D 2MnO2 1 4KOH 1 O2 Cr2O722 1 14H1 1 6I2 3d Sc Ti V Cr Mn Fe Co Ni Cu Zn U (i) S U (ii) ? (iii) (iv) (a) Account for the following : 13 13 S ? S U ? (i) Mn shows the highest oxidation state of17 with oxygen but with fluorine it shows the highest oxidation state of 14. (ii) Cr21 is a strong reducing agent. (iii) Cu21 salts are coloured while Zn21 salts are white. (b) Complete the following equations : (i) (ii) 56/1/C D 2MnO2 1 4KOH 1 O2 Cr2O722 1 14H1 1 6I2 14 OR The elements of 3d transition series are given as : Sc Ti V Cr Mn Fe Co Ni Cu Zn Answer the following : (i) Write the element which shows maximum number of oxidation states. Give reason. (ii) Which element has the highest m.p ? (iii) Which element shows only 13 oxidation state ? (iv) Which element is a strong oxidizing agent in 13 oxidation state and why ? 26. (a) (b) (c) A U B U H ,Pd2BaSO H N2OH (i) 2 4 A 2 CH3COCl B (ii) CH3 MgBr 1. CO2 A 2. H3O1 5 PCl 5 B (i) C6H52COCH3 U C6H52CHO (ii) CH3COOH U HCOOH CH3CHO, CH3COOH, CH3CH2OH (a) (b) - U U S C6H5COCH3, CH32CHO, CH3COCH3 (c) (d) , ? 1. (i2Bu) AlH 2 CH3CH2CH5CH2CH2CN 2. H2O (e) 56/1/C C3H6O A U B NaOH U I2, U U B U A A U B 15 P.T.O. (a) (b) (c) Write the structures of A and B in the following reactions : H ,Pd2BaSO H N2OH (i) 2 4 A 2 CH3COCl B (ii) CH3 MgBr PCl 1. CO2 A 2. H3O1 5 B Distinguish between : (i) C6H52COCH3 and C6H52CHO (ii) CH3COOH and HCOOH Arrange the following in the increasing order of their boiling points : CH3CHO, CH3COOH, CH3CH2OH OR (a) Write the chemical reaction involved in Wolff-Kishner reduction. (b) Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction : C6H5COCH3, CH32CHO, CH3COCH3 (c) Why carboxylic acid does not give reactions of carbonyl group ? (d) Write the product in the following reaction 1. (i2Bu) AlH 2 CH3CH2CH5CH2CH2CN 2. H2O (e) 56/1/C A and B are two functional isomers of compound C3H6O. On heating with NaOH and I2, isomer B forms yellow precipitate of iodoform whereas isomer A does not form any precipitate. Write the formulae of A and B. 16

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