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

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SET-1 Series ONS U . Code No. U . 56/1/N 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 15 - 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 15 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/N Maximum Marks : 70 1 P.T.O. (i) (ii) (iii) 6 (iv) 11 (v) 23 U U (vi) 24 26 - U U (vii) , U U U U 1 5 - U U 10 - U U 22 2 1 - U U 3 4 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/N 2 1. SN2 U ? (i) (ii) Which of the following two reactions is SN2 and why ? (i) (ii) 2. U U U U U U U m U Pb(NO3)2 On heating Pb(NO3)2 a brown gas is evolved which undergoes dimerization on cooling. Identify the gas. 3. U U ZnO U ? ZnO turns yellow on heating. Why ? 56/1/N 3 P.T.O. 4. . . . . . Write the IUPAC name of the given compound : 5. U S U U Write the reason for the stability of colloidal sols. 6. (i) L U (ii) U U ? (i) Write the colligative property which is used to find the molecular mass of macromolecules. (ii) 7. In non-ideal solution, what type of deviation shows the formation of minimum boiling azeotropes ? U (i) (HPO3)3 (ii) XeF4 Write the structures of the following : (i) 8. (HPO3)3 (ii) XeF4 NiCl2.6H2O AgNO3 U AgCl (i) U (ii) . . . . . 56/1/N 4 When a coordination compound NiCl2.6H2O 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 N (g) 1 3H (g) 2NH3 (g) 2 2 U 5 k (i) U U (ii) k U Pt N (g) 1 3H (g) For a reaction : 2NH3 (g) 2 2 Rate 5 k 10. (i) Write the order and molecularity of this reaction. (ii) Write the unit of k. U U (i) (ii) U - U U U M U U (i) U (ii) U U Write the chemical equations involved in the following reactions : (i) Kolbe s reaction (ii) Friedal - Crafts acetylation of anisole OR How do you convert : (i) Phenol to toluene (ii) Formaldehyde to Ethanol 56/1/N 5 P.T.O. 11. 400 pm U f.c.c. S U 7 g cm23 280 g U ? An element crystallizes in a f.c.c. lattice with cell edge of 400 pm. The density of the element is 7 g cm23. How many atoms are present in 280 g of the element ? 12. H2O2 U U U S U U log k 5 14.2 2 1.0 3 104 K T Ea U U S U k U 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 3 104 K T Calculate Ea for this reaction and rate constant k if its half-life period be 200 minutes. (Given : R58.314 JK21 mol21) 13. U (i) O/W (ii) U U (iii) U Define the following terms : (i) O/W Emulsion (ii) Zeta potential (iii) Multimolecular colloids 56/1/N 6 14. (i) Uc U h U U (ii) ? (iii) U S U c U ? (i) Name the method of refining which is based on the principle of adsorption. (ii) What is the role of depressant in froth floatation process ? (iii) What is the role of limestone in the extraction of iron from its oxides ? 15. 50 g Na2SO4 (M5142 g mol21) 2 g U U Na2SO4 U U U U ( Kb 50.52 K kg mol21) Calculate the boiling point of solution when 2 g of Na2SO4 (M5142 g mol21) was dissolved in 50 g of water, assuming Na 2SO 4 undergoes complete ionization. (Kb for water50.52 K kg mol21) 16. U U H3PO2 U (i) H3PO4 (ii) U o (iii) U HF HI U Assign reason for the following : (i) H3PO2 is a stronger reducing agent than H3PO4. (ii) Sulphur shows more tendency for catenation than Oxygen. (iii) Reducing character increases from HF to HI. 56/1/N 7 P.T.O. 17. (i) (ii) (iii) Write the major monohalo product(s) in each of the following reactions : (i) (ii) (iii) 56/1/N 8 18. U (a) U U U U U (b) U U U (c) HI U U U U U CH3OH. CH32I Give reasons for the following : 19. (a) Protonation of Phenols is difficult whereas ethanol easily undergoes protonation. (b) Boiling point of ethanol is higher than that of dimethyl ether. (c) Anisole on reaction with HI gives phenol and CH32I as main products and not iodobenzene and CH3OH. A, B U C U (i) D Br2/KOH C6H5 2 COO2NH1 A B 4 (ii) Sn/HCl 2 3 2 C6 H5N1 A B C 2 BF4 CHCl 1alc. KOH NaNO /Cu D Write the structures of A, B and C in the following reactions : (i) D Br2/KOH CH3COCl/pyridine C6H5 2 COO2NH1 A B C 4 (ii) Sn/HCl 2 3 2 C6 H5N1 A B C 2 BF4 56/1/N CHCl 1alc. KOH NaNO /Cu D 9 P.T.O. 20. (i) (ii) U U U ? (iii) U U S -6, 6, , -S U U U (i) What is the role of benzoyl 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 : Nylon-6, 6 Polythene, Buna-S OR Write the mechanism of free radical polymerization of ethene. (iii) o U m U U ? - U U- U (i) Write one reaction of D-Glucose which cannot be explained by its open 21. (i) (ii) D- chain structure. (ii) What type of linkage is present in Nucleic acids ? (iii) Give one example each for water-soluble vitamins and fat-soluble vitamins ? 56/1/N 10 22. (a) [Fe(CN)6]42 U , U U S U ( . . Fe526) (b) [Co(en)2Cl2]1 (a) For the complex [Fe(CN)6]42, write the hybridization, magnetic character and spin type of the complex. (At. number : Fe526) (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 U M U S U U S U U U U M U S S S U U U U (i) U ( ) ? (ii) U U U ? (iii) U ? U 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. 56/1/N 11 P.T.O. 24. (a) 298 K U E8cell U 2Cr(s)1 3Fe21(0.01M) 2Cr31(0.01M) 1 3Fe(s) (b) : Ecell50.261 V U B E8 U U U U U ? A [E8(Fe21/Fe)520.44 V] U E8(A21/A)522.37V : E8(B21/B)520.14 V (a) CH3COOH 0.001 mol L21 3.90531025 S cm21 U U (a) U U l8(H1)5349.6 S cm2 mol21 U l8 (CH3COO2)540.9 S cm2 mol21. (b) l U U l U E8cell s (a) Calculate E8cell for the following reaction at 298 K : 2Cr(s)1 3Fe21(0.01M) 2Cr31(0.01M) 1 3Fe(s) Given : Ecell50.261 V (b) Using the E8 values of A and B, predict which one is better for coating the surface of iron [E8(Fe21/Fe)520.44 V] to prevent corrosion and why ? Given : E8(A21/A)522.37 V : E8(B21/B)520.14 V 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 l8(H1)5349.6 S cm2 mol21 and l8 (CH3COO2)540.9 S cm2 mol21. (b) 56/1/N Define electrochemical cell. What happens if external potential applied becomes greater than E8cell of electrochemical cell ? 12 25. (a) (b) U S c U (i) Mn S 17 U S 14 U (ii) U (iii) U U U U (i) D 2MnO2 14KOH1O2 (ii) Cr2O722 114H116I2 3d Sc Ti V Cr Mn Fe Co Ni Cu Zn U (i) U (ii) ? (iii) (iv) (a) Account for the following : 13 11 S S U ? (i) Mn shows the highest oxidation state of 17 with oxygen but with fluorine it shows the highest oxidation state of 14. (ii) Zirconium and Hafnium exhibit similar properties. (iii) Transition metals act as catalysts. (b) 56/1/N Complete the following equations : (i) D 2MnO2 14KOH1O2 (ii) Cr2O722 114H116I2 13 P.T.O. 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 is not regarded as a transition element. Give reason. (ii) Which element has the highest m.p ? (iii) Write the element which can show an oxidation state of 11. (iv) Which element is a strong oxidizing agent in 13 oxidation state and why ? 26. (a) (b) (c) A, B, C U D U U C6H52CH5CH2CO CH2CH3 (i) C6H52CH5CH2COCH3 (ii) CH3CH2COOH U HCOOH CH3CH2OH, CH3COCH3, CH3COOH (a) U U U (b) S CH32CHO, C6H5COCH3, HCHO (c) 56/1/N Cl2CH22COOH pKa CH3COOH 14 pKa ? (d) 1. (i-Bu) AlH 2 CH3CH 2CH5CH2CH2CN 2.H O 2 (e) C3H6O A U B NaOH U I2 U U A U B A U B (a) Write the structures of A, B, C and D in the following reactions : (b) Distinguish between : (c) (i) C6H52CH5CH2COCH3 and C6H52CH5CH2CO CH2CH3 (ii) CH3CH2COOH and HCOOH Arrange the following in the increasing order of their boiling points : CH3CH2OH, CH3COCH3, CH3COOH OR (a) Write the chemical reaction involved in Etard reaction. (b) Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction : CH32CHO, C6H5COCH3, HCHO (c) Why pKa of Cl2CH22COOH is lower than the pKa of CH3COOH ? (d) Write the product in the following reaction. 1. (i-Bu) AlH 2 CH3CH 2CH5CH2CH2CN 2.H O 2 (e) 56/1/N A and B are two functional isomers of compound C3H6O. On heating with NaOH and I2, isomer A forms yellow precipitate of iodoform whereas isomer B does not form any precipitate. Write the formulae of A and B. 15 P.T.O.

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