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CBSE Class 12 Board Exam 2015 : Chemistry

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SET 1 . Series : SSO/C Code No. 56/1 - - . Roll No. Candidates must write the Code on the title page of the answer-book. - 12 - - - - 26 , - 15 - 10.15 10.15 10.30 - - Please check that this question paper contains 12 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 minutes 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. ( ) CHEMISTRY (Theory) : 3 ] [ Time allowed : 3 hours ] : 70 [ Maximum Marks : 70 : (i) (ii) - 1 5 - 1 - 6 10 - 2 - 11 22 - 3 - 23 4 - 24 26 - 5 , (iii) (iv) (v) (vi) (vii) 56/1 1 [P.T.O. General Instructions : 1. (i) All questions are compulsory. (ii) Question number 1 to 5 are very short answer questions and carry 1 mark each. (iii) Question number 6 to 10 are short answer questions and carry 2 marks each. (iv) Question 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) Question 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. AgCl ? What type of stoichiometric defect is shown by AgCl ? 2. ? What are emulsions ? Give an example. 3. ? What is meant by chelate effect ? 4. (IUPAC) : CH3 CH2 CHO Write the IUPAC name of the following : CH3 CH2 CHO 5. : , p- p- Arrange the following in increasing order of basic strength : Aniline, p-Nitroaniline and p-Toluidine 56/1 2 6. : (i) (x) (ii) (m) Define the following terms : 7. (i) Mole fraction (x) (ii) Molality of a solution (m) mol L 1 Write units of rate constants for zero order and for the second order reactions if the concentration is expressed in mol L 1 and time in second. 8. : (i) (ii) NF3 NCl3 Explain the following : 9. (i) Nitrogen is much less reactive than phosphorus. (ii) NF3 is an exothermic compound but NCl3 is an endothermic compound. ? (i) (ii) H2S 56/1 3 [P.T.O. Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with oxalic acid ? Write the ionic equations for the reactions. OR Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with (i) an iodide (ii) H2S. 10. Write the mechanism of acid dehydration of ethanol to yield ethene. 11. fcc 4.077 10 8 cm , (r) Silver crystallises in fcc lattice. If edge length of the unit cell is 4.077 10 8 cm, then calculate the radius of silver atom. 12. - (M.W. 342) 5 ( ) X 0.877% X A 5 percent solution (by mass) of cane-sugar (M.W. 342) is isotonic with 0.877% solution of substance X. Find the molecular weight of X. 13. 60 s 1 1/10 ? The rate constant for a first order reaction is 60 s 1. How much time will it take to reduce the initial concentration of the reactant to its 1/10th value ? 56/1 4 14. : (i) (ii) (iii) Describe the following processes : (i) Dialysis (ii) Electrophoresis (iii) Tyndall effect 15. : (i) ? (ii) (iii) ? Answer the following : (i) What is the role of cryolite in the metallurgy of aluminium ? (ii) Differentiate between roasting and calcination. (iii) What is meant by the term chromatography ? OR Write the reactions taking place in different zones of the blast furnace to obtain Iron. 16. ? What is meant by disproportionation ? Give one example of disproportionation reaction in aqueous solutions. 56/1 5 [P.T.O. 17. IUPAC : (i) [Co(NH3)6]Cl3 (ii) [NiCl4]2 (iii) K3[Fe(CN)6] Write the IUPAC name of the following : (i) [Co(NH3)6]Cl3 (ii) [NiCl4]2 (iii) K3[Fe(CN)6] 18. (IUPAC) : (i) CH3 CH CH2 CH3 | Br Br (ii) Br (iii) CH2 = CH CH2 Cl Give the IUPAC names of the following compounds : (i) CH3 CH CH2 CH3 | Br Br (ii) Br (iii) CH2 = CH CH2 Cl 56/1 6 19. ? (i) (ii) -1- (iii) -2- How are the following conversions carried out ? (i) Benzyl chloride to Benzyl alcohol (ii) Ethyl magnesium chloride to Propan-1-ol (iii) Propene to Propan-2-ol 20. : (i) PCl5 CH3 CH2OH ? OH anhyd. AlCl3 + CH3 Cl ? (ii) (iii) CH3 Cl + CH3CH2 ONa ? Write the major product in the following equations : (i) PCl5 CH3 CH2OH ? OH (ii) anhyd. AlCl3 + CH3 Cl ? (iii) CH3 Cl + CH3CH2 ONa ? 21. : (i) (ii) (iii) Define the following as related to proteins : (i) Peptide linkage (ii) Primary structure (iii) Denaturation 56/1 7 [P.T.O. 22. Explain the term copolymerization and give two examples of copolymerization. 23. , (i) (ii) ? (iii) ? Neeraj went to the departmental store to purchase groceries. On one of the shelves he noticed sugar free tablets. He decided to buy them for his grandfather who was a diabetic. There were three types of sugar free tablets. He decided to buy sucrolose which was good for his grandfather s health. (i) Name another sugar free tablet which Neeraj did not purchase. (ii) Was it right to purchase such medicines without doctor s prescription ? (iii) What quality of Neeraj is reflected above ? 24. rG e.m.f.(E) 25 C : Zn(s) | Zn2+(aq) || Sn2+(aq) | Sn(s) : E = 0.76 V; E 2+ = 0.14 V Zn2+/Zn Sn /Sn F = 96500 C mol 1 56/1 8 (a) - (b) : Fe2+(aq) + Ag+(aq) Fe3+(aq) + Ag(s) rG (E + = 0.80 V; E 3+ 2+ = 0.77 V) Ag /Ag Fe /Fe Calculate rG and e.m.f. (E) that can be obtained from the following cell under the standard conditions at 25 C : Zn(s) | Zn2+(aq) || Sn2+(aq) | Sn(s) Given : E = 0.76 V; E 2+ = 0.14 V Zn2+/Zn Sn /Sn and F = 96500 C mol 1. OR (a) Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration. (b) Calculate the standard cell potential of the galvanic cell in which the following reaction takes place : Fe2+(aq) + Ag+(aq) Fe3+(aq) + Ag(s) Calculate the rG and equilibrium constant of the reaction also. (E + = 0.80 V; E 3+ 2+ = 0.77 V) Ag /Ag Fe /Fe 56/1 9 [P.T.O. 25. (a) 16 15 ? (b) (i) H2SO4 CaF2 ? (ii) ? (iii) Ca(OH)2 ? (a) (b) : (i) BrF3 (ii) XeO3 : (i) PH3 NH3 ? (ii) ? (iii) XeOF4 (a) Elements of Gr. 16 generally show lower value of first ionization enthalpy compared to the corresponding periods of Gr. 15. Why ? (b) What happens when (i) concentrated H2SO4 is added to CaF2 ? (ii) sulphur dioxide reacts with chlorine in the presence of charcoal ? (iii) ammonium chloride is treated with Ca(OH)2 ? OR 56/1 10 (a) (b) Draw the structure of the following : (i) BrF3 (ii) XeO3 Answer the following : (i) Why is NH3 more basic than PH3 ? (ii) Why are halogens strong oxidising agents ? (iii) Draw the structure of XeOF4. 26. (a) (b) : (i) p- (ii) 4- -3- -2- : (i) (ii) (iii) (a) (b) : (i) (ii) CH3CHO ? (i) CH3 CH3 (ii) CH3 CH CH2 CHO | OH (iii) CH3CH2OH 56/1 11 [P.T.O. (a) (b) Draw the structures of the following : (i) p-Methylbenzaldehyde (ii) 4-Methylpent-3-en-2-one Give chemical tests to distinguish between the following pairs of compounds : (i) Benzoic acid and Ethyl benzoate. (ii) Benzaldehyde and Acetophenone. (iii) Phenol and Benzoic acid. OR (a) (b) Draw the structures of the following derivatives : (i) Propanone oxime (ii) Semicarbazone of CH3CHO How will you convert ethanal into the following compounds ? Give the chemical equations involved. (i) CH3 CH3 (ii) CH3 CH CH2 CHO | OH (iii) CH3CH2OH _________ 56/1 12

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