IIT JAM Chemistry Past Papers 2005-2018 (PDF)
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This document is a collection of IIT JAM 2005 Chemistry paper. It contains multiple choice and subjective questions covering various topics of chemistry.
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PAPER : IIT-JAM 2005 1 PAPER : IIT-JAM 2005 CHEMISTRY-CY [PAPER] NOTE: Attempt ALL the 44 questions. Questions 1-30 (Objective questions) carry three marks each a...
PAPER : IIT-JAM 2005 1 PAPER : IIT-JAM 2005 CHEMISTRY-CY [PAPER] NOTE: Attempt ALL the 44 questions. Questions 1-30 (Objective questions) carry three marks each and questions 31-44 (Subjective questions) carry fifteen marks each. 1. Arrange the following in the decreasing order of acidity of the hydrogen indicated in italic (i) CH 3COCH 3 (ii) CH3COCH 2COCH 3 (iii) CH 3OOCCH 2COOCH3 (iv) CH3COCH 2 NO 2 (a) (ii) > (iii) > (i) > (iv) (b) (iv) > (ii) > (iii) > (i) (c) (iv) > (iii) > (ii) > (i) (d) (ii) > (iv) > (iii) > (i) 2. For the reaction shown below if the concentration of KCN is increased four times, the rate of the reaction will be Me Me aq. MeOH Cl + KCN CN + KCl Me Me (a) doubled (b) increased four times (c) unaffected (d) halved. 3. Benzyl chloride is reacted with different nucleophiles shown below. Arrange them in decreasing order of reactivity. Nucleophilies: HO , CH 3COO , PhO , CH3O (a) CH 3O HO PhO CH 3COO (b) HO CH 3O PhO CH 3COO (c) HO PhO CH 3O CH 3COO (d) CH 3COO CH 3O HO PhO 4. The rate of nitration of the following aromatic compounds decreases in the order (i) benzene (ii) pyridine (iii) thiophene (iv) toluene (a) (iv) > (i) > (iii) > (ii) (b) (iii) > (iv) > (i) > (ii) (c) (iii) > (ii) > (i) > (iv) (d) (ii) > (i) > (iv) > (iii) 5. The major product formed in the reaction of 1, 3-butadiene with bromine is (a) BrCH 2CH Br CH CH 2 (b) CH 2 CH – CH 2CH 2 Br (c) CH 2 C Br – C Br CH 2 (d) BrCH 2CH CHCH 2 Br 6. The reaction of (+) 2-iodobutane and NaI* (I* is radioactive isotope of iodine) in acetate was studied by measuring the rate of racemization (kr) and the rate of incorporation of I*(ki). CH3CH I CH 2CH3 NaI* CH3CH I * CH 2CH 3 NaI For this reaction, the relationship between kr and ki is: (a) ki 2 kr (b) ki 1/ 2 kr (c) ki kr (d) ki 1/ 3 kr 2 PAPER : IIT-JAM 2005 Ba(OH)2 7. DNA (P) MgO/ HCl PO43– + (Q) (R) + (S) + sugar In the scheme shown above (P), (Q), (R) and (S) are (a) (P) = purine bases, (Q) pyrimidine bases, (R) = nucleotides, (S) = nucleosides (b) (P) = nucleosides,m (Q) = nucleotides, (R) = pyrimidine bases, (S) = purine bases. (c) (P) = nucleosides, (Q) = nucleotides, (R) = (S) = purine bases. (d) (P) = nucleotides, (Q) = nucleosides, (R) = pyrimidine base, (S) = purine base. 8. The products obtained from the following reaction are: O H+ Ph OC2H5 + H218 O O O + C2H5OH (a) Ph (b) 18 + C2H5OH OH Ph OH O O 18 18 (c) + C2H5 OH (d) 18 + C2H5 OH Ph OH Ph OH 9. The product(s) obtained in the following reaction is (are) O OH OH (a) + (b) HO OH OH OH (c) (d) + PAPER : IIT-JAM 2005 3 10. Match the isoelectric point with the amino acids. Amino acid Isoelectric point (X) H 2 NCH 2 COOH (I) 9.5 (Y) HOOCCH 2CH 2 CH NH 2 COOH (II) 6.0 (Z) H 2 N CH 2 4 CH NH 2 COOH (III) 3.1 (a) (X)-(II), (Y)-(III), (Z)-(I) (b) (X)-(III), (Y)-(I), (Z)-(II) (c) (X)-(I), (Y)-(II), (Z)-(III) (d) (X)-(III), (Y)-(I), (Z)-(III) 11. The compound having the highest melting point is: (a) LiCl (b) LiF (c) LiI (d) LiBr 12. The shape of SF4 is: (a) tetrahedral (b) trigonal bipyramidal (c) square planer (d) octahedral. 13. The degree of hydration is expected to be maximum for (a) Mg 2 (b) Na (c) Ba 2 (d) K 14. The decreasing order of the first ionization energy of the following elements is: (a) Xe > Be > As > Al (b) Xe > As > Al > Be (c) Xe > As > Be > Al (d) Xe > Be > Al > As 15. The radioactive isotope used to locate brain tumors is: (a) 12 D (b) 15 7 N (c) 131 53 I (d) 13 6 C 7 16. The crystal field stabilization energy of high spin d octahedral complex is: 4 4 9 9 (a) 0 2 P (b) 0 3P (c) 0 2 P (d) 0 3P 5 5 5 5 17. The complex with the most colour among the following is: 3 2 2 3 (a) FeF6 (b) MnCl4 (c) CoCl4 (d) CoF6 18. On addition of a solution of AgNO3 to a solution of Na2S2O3, it turns black on standing due to the formation of : (a) Ag (b) Ag2S (c) Ag2S2O2 (d) Ag2SO4. 19. Among the following complexes, (i) Ru bipyridyl 3 (ii) Cr EDTA 3 3 (iii) trans CrCl2 oxalate 2 (iv) cis CrCl2 oxalate 2 the ones that show chirality are (a) (i), (ii), (iv) (b) (i), (ii), (iii) (c) (ii), (iii), (iv) (d) (i), (iii), (iv) 20. The electronic configurations that have orbital angular momentum contribution in octahedral envi- ronment are (a) d1 and high spin d4 (b) d1 and d2 (c) d2 and high spin d6 (d) high spin d4 and high spin d6. 21. For an ideal solution formed by mixing of pure liquids A and B. (a) H mixing 0 (b) H mixing 0 (c) H mixing 0 (d) S mixing 0 4 PAPER : IIT-JAM 2005 22. The relationship between the equilibrium constant K1 for the reaction: 1 CO2 g CO g O2 g 2 and the equilibrium constant K2 for the reaction: 2CO2 g is: 2CO g O2 g (a) 2K1 K 2 (b) K1 K22 (c) K1 K 2 (d) K12 K 2 23. For H-like atoms, the ground state energy is proportional to Z2 1 (a) 2 (b) (c) Z 2 (d) Z Z 2 Where is the reduced mass and Z is the nuclear charge. 24. The value of integral e x x 2 dx is 1 2 x 2 x x (a) x e 2 xe 2e x (b) 2 x e 2 xe x 2e x 1 2 x (c) 2 x e 2 xe x 2e x (d) x2 e x 2 xe x 2e x 1 25. For the reaction aA products , the plot of A versus time (t) gives a straight line. Order of the reaction is: (a) 0 (b) 1 (c) 2 (d) 3 26. The pH of a solution prepared from 0.005 mole of Ba(OH)2 in 100 cc water is: (a) 10 (b) 12 (c) 11 (d) 13 27. For an electron whose x-positional uncertainity is 1×1010 m, the uncertainity in x-component of the velocity in ms–1 will be of the order of (Data: me 9 1031 kg , h 6.6 1034 Js ) (a) 106 (b) 109 (c) 1012 (d) 1015. 28. CaO s CO2 g For the following system in equilibrium, CaCO3 s the number of components, (C), phases (P) and degrees of freedom (F), respectively, are (a) 2, 2, 2 (b) 1, 3, 0 (c) 3, 3, 2 (d) 2, 3, 1 29. For the distribution of molecular velocities of gases, identify the correct order from following (where v mp , vav , v rms are the most probable velocity, average velocity root mean square velocity, respec- tively): (a) v rms , vav , vmp (b) v mp , vrms , vav (c) v av , v rms , vmp (d) v mp , vav , v rms 30. Given that E0 0.44V and E0 0.77V, the E0 is : Fe2 /Fe Fe3 /Fe2 Fe3 /Fe (a) 1.21 V (b) 0.33 V (c) –0.036 V (d) 0.036 V PAPER : IIT-JAM 2005 5 31. Identify the major product(s) formed in the following reactions. Intermediates and reaction mecha- nisms need not be discussed. O (a) Me 1. NH2OH.HCl 2. H2SO4/ Me CHO NaOEt (b) + O CHO Me O (i) HNO3/H2SO4 (c) O Me (ii) H3O+/ 32. How may the following transformations be effected? Indicate the reagents/reaction conditions clearly in each step. (a) (Not involving any functional group transformation of the COOH group in the starting material) Br COOH Br COOH Br (b) (Using diethyl malonate as the only source of carbon) COOEt CH2COOH H2C CH2COOH COOEt (c) HO NH2 33. Suggest a suitable mechanism for each of the following reactions. Ph Me (a) PhCOCH2CH3 + Ph NaOEt C C COOEt EtOH Ph O O OH Cl (b) HCl 6 PAPER : IIT-JAM 2005 34. Rationalize the following observations using suitable mechanism. (a) Nitration of 4 t-butyltoluene gives 4-nitrotoluene as one of the products. (b) cis-1-t-butylcyclohexyltrimethylammonium hydroxide undergoes Hoffmann elimination to yield 4-t-butylcyclohexene whereas the trans isomer does not (use conformations) explain. 1.dry ether (c) PhMgBr 2PhCHO 2. acid workup PhCOPh PhCH2 OH 35. (a) Suggest a chemical method for the separation of a mixture contain p-N, N-dimethylaminophenol and p-aminobenzoic acid and give a confirmatory test for phenol. (b) Write the structures of X, Y and Z in the following 1. NaNO2/dil. HCl, 0ºC (i) NH2 X 2.-naphthol/NaOH NaNO2/dil. HCl (ii) NHMe Y NaNO2/dil. HCl (iii) NMe2 Z 36. (a) Predict the hybridization and draw the structure of the following molecules based on VSEPR theory (i) I3 (ii) SO32 (iii) P CH 3 3 F2 (b) Explain why PCl5 exists and PH5 does not. 37. (a) Write balanced equations for the formation of 4 3 (i) P2O74 from PO43 (ii) H 2O 4 Fe OH 2 Fe OH2 4 from Fe OH2 6 (b) Which one of the two solutions has lower pH? Justify your answer. (i) 0.1 M Fe(ClO4)2 or 0.1 M Fe(ClO4)3. (ii) 0.1 M Hg(NO3)2 or 0.1 M Zn(NO3)2. 2 38. (a) Between Co H 2O 6 and Cu H 2O 2 , which has more distorted structure and why? 6 (b) Calculate CFSE (in unis of 0 ) and spin only magnetic moment for the following complexes. 3 3 2 (i) CoF6 (ii) Fe CN 6 (iii) NiCl4 39. (a) The radioactive element Ra (Z = 86) emits three alpha particles in succession. Deduce in which group the resulting element will be found? (b) A radioisotope sample has an initial activity of 23 dis/min. After 1/2 h, the activity is 11.5 dis/ min. How many atoms of the radioactive nuclide were present originally? t 1 0.69 2 40. (a) Write the products of the following reactions: (i) CH 3I HO (ii) CF3I HO (iii) 2CF3 I Na Mn CO 5 (b) Arrange BF3, BCl3 and BBr3 in the increasing order of Lewis acidity and justify. PAPER : IIT-JAM 2005 7 41. Justify the following: (a) Considering CO2 as an ideal gas, equipartition theorem products its total energy as 6.5 kT. (b) S for a process is the same whether the process takes place reversibly or irreversibly.. (c) The quantity G equals the maximum non-expansion work done by a system in a constant temperature-pressure process. (d) At constant temperature and pressure, G 0 for a reversible phase change. (e) Transition states cannot be isolated as independent chemical species. 3000 42. The rate constant k for a second order reaction P Q products is expressed log10 k 20 , T where the concentration is in mol lit –1, T is in absolute temperature and time is in minutes. The initial concentrations of both the reactants are 0.05 M. Calculate the activation energy and half life of the reaction at 27ºC. (R=2 cal K–1 mol–1). 43. The equilibrium constant for the reaction. 3FeO s CO 2 g Fe3O 4 s CO g at 600ºC is 1.00. If a mixture intially consisting of 1 mole of Fe3O 4 , 2 moles of CO, 0.5 of FeO and 0.3 mole of CO2 is heated to 600ºC at constant total pressure of 5 atmosphere, how many moles of each substance would be present at equilibrium? 44. (a) Use the time-independent Schrodinger equation to calculate the energy of a particle of mass ‘m’ 8 x y z with V = 0 in the state 3 sin sin sin in a cubical box of length ‘a’. a a a a (b) At 20ºC, the vapour pressure of two pure liquids X and Y which form an ideal solution are 70 torr and 20 torr respectively. If the mole fraction of X in solution is 0.5, find the mole fraction of X and Y in the vapor phase in equilibrium with the solution. CHEMISTRY IIT-JAM Chemistry Paper-2006 Instruction: Q.1-30 (Objective questions) carry three marks each and Q.31-44 (Subjective questions) carry fif- teen marks each. 1. After the following interchanging of groups in the Fischer projection of 2-bromobutane, the configuration of (X) and (Y) will be Br CH3 CH3 H CH3 H Br H C2H5 C2H5 C2H5 Br (X) (Y) (a) X = R, Y = S (b) X = R; Y = R (c) X = S; Y = R (d) X = S; Y = S CHO Br2/FeBr3 2. The major product of the reaction OH CHO CHO CHO CHO Br Br (a) (b) (c) (d) OH OH Br OH OH Br 3. In the reaction sequence C2 H5ONa (i) OH CH 3COCH 2COOCC2 H5 CH Br (X) 3 Y (ii) H 2O/H The product (Y) is: (a) CH 3COCH 2COOCH3 (b) CH3COCH CH3 2 (c) CH3COCHCOOH (d) CH 3COC2 H 5 CH3 4. The major product (X) in the reaction CH3 CH3 AlCl3 (X) (trace of H2O) 25ºC is: CH3 OH CH3 (a) (b) (c) (d) H3C CH3 OH 1 CHEMISTRY 5. The product of the reaction AlCl3 /Cu 2Cl2 C6 H6 CO HCl heat gives positive test with Fehling’s solution. The product is: (a) C6 H 5OH (b) C6 H 4 Cl CHO (c) C6 H 4 OH CHO (d) C6 H5CHO 6. The compound (X) in the reaction sequence CH2COONa P2S3 Rancy Ni (X) CH3CH2CH2CH3 CH2COONa heat CH2COOH (a) (b) (c) (d) S CH2COOH S S 7. The major product of the reaction H+ OH OH O (a) (b) (c) (d) OH 8. The increasing order of the acidity of the hydrogen marked in bold italics among the following is: H H H H H I II H III (a) III < II < I (b) II < I < III (c) I < II < III (d) II < III < I 9. The major product of the reaction HBr is: Br (a) (b) (c) (d) Br Br Br 10. The number of m enantiomers of camphor O (a) Four (b) Two (c) Three (d) One 2 CHEMISTRY 11. The decreasing order of the first ionization energy of the following elements is (a) He > H > Be > B (b) Be > B > H > He (c) H > He > Be > B (d) B > Be > He > H 12. If the values of Madelung constants of the following compounds are equal, then their lattice energy values decrease in the order (a) KCl > NaF > CaO > Al2O3 (b) Al2O3 > CaO > NaF > KCl (c) NaF > KCl > CaO > Al2O3 (d) Al2O3 > CaO > KCl > NaF 13. The fluoride, whose value of dipole moment is NOT equal to zero, is: (a) XeF4 (b) CF4 (c) SF4 (d) PF5. 14. The decreasing order of ionic nature of the following compound is: (a) Lil > NaBr > KCl > CsF (b) Lil > KCl > NaBr > CsF (c) CsF > NaBr > KCl > Lil (d) CsF > KCl > NaBr > Lil 15. The atomicity and the total number of bonds in the elemental white phoshorus molecule are respectively, (a) 4 and 6 (b) 6 and 4 (c) 4 and 4 (d) 6 and 6 16. The octahedral crystal field splitting 0 of d orbital energies of the follwoing metal ions decreases in the order (a) Co 2 Co3 Rh 3 (b) Rh 3 Co3 Co2 (c) Rh 3 Co 2 Co3 (d) Co3 Co 2 Rh 3 17. The half-life of a radioactive nuclide is 20 years. If a sample of this nuclide has an activity of 6400 disinte- grations per minute (dis/min) today, its activity (dis/min) after 100 years would be (a) 850 (b) 1600 (c) 200 (d) 400 18. The average value of C–C bond order in graphite is: (a) 1 (b) 3/2 (c) 3/4 (d) 4/3 19. The optical absorption spectrum of [Ti(H2O)6]3+ has its absorption maximum at 20300 cm–1. The magnitude of the crystal field stabilization energy in cm–1 is: (a) 8120 (b) 16240 (c) 24360 (d) 50750 20. In inorganic qualitative analysis, H2S in acidic medium will NOT precipitate. (a) HgS (b) ZnS (c) CuS (d) CdS 21. The phase diagram of a pure substance is sketched below. P P2 P3 P1 T The number of degrees of freedom at points P1, P2 and P3, respectively, are (a) 2, 1, 0 (b) 1, 2, 0 (c) 2, 0, 1 (d) 0, 2, 1 22. The solubility products (Ksp) for three salts MX, MY2 and MZ3 are 1×10–8, 4×10–9 and 27×10–8, respectively. The solubilities of these salts follow the order (a) MX > MY2 > MZ3 (b) MZ3 > MY2 > MX (c) MZ3 > MX > MY2 (d) MY2 > MX > MZ3. 3 CHEMISTRY 23. The temperature (T) dependence of the equilibrium constant (K) of a chemical reaction is correctly described by the following statement: (a) For an endothermic reaction, the slope of ln K vs 1/T plot is positive. (b) For an exothermic reaction, K is proportional to T. (c) For an exothermic reaction, K at a higher temperature is lower than K at a lower temperature. (d) If H is independent of temperature, the change in K with T is smaller at lower temperatures. 24. When the concentration of K+ across a cell membrane drops from 0.01 M to 0.001 M, the potential difference across the membrane is: (a) 0.0 V (b) 0.0059 V (c) 0.059 V (d) 0.59 V 25. The statement that is correct for both electrochemical (galvanic) cells and electrolytic cells is (a) G nFE (b) Free energy decreases in both cells. (c) The cell potentials are temperature independent (d) Chemical energy is converted into electrical energy in both cells. 26. The molar heat capacity at constant volume of a colourless gas is found to be 25 J.mol–1 K–1 at room tempera- ture. The gas must be (a) N2 (b) O2 (c) CO2 (d) SO2. 1/2 27. The wavelength for a particle (moving in a ring) is 2 exp 2i , where is the polar angle. The probability of finding the particle in a small interval d when the value of / 2 is: (a) d (b) d / 2 (c) d exp i (d) d exp i / 2 28. An electric current of 0.965 ampere is passed for 2000 seconds through a solution containing Cu CH3CN and metallic copper is deposited at the cathode. The amount of Cu deposited is 4 (a) 0.005 mol (b) 0.01 mol (c) 0.02 mol (d) 0.04 mol 29. The Maxwell-Boltzmann distribution for molecular speeds is shown in the following figure. f(v) HW L v In the figure, H is the height of the peak, L is the location of the maximum and W is the width at half height. As the temperature is decreased, (a) H increases, L deceases and W increases (b) H increases, L decreases and W decreases. (c) H decreases, L decreases and W increases (d) H decreases, L decreases and W decreases. 30. A system undergoes two cyclic processes 1 and 2. Process 1 is reversible and process 2 is irreersible. The correct statement relating to the two processes is: (a) S (for process 1) = 0, while S (for process 2) 0 (b) q cycle 0 for process 1 and q cycle 0 for process 2. (c) More heat can be converted to work in process 1 than in process 2. (d) More work can be converted to heat in process 1 than in process 2. 4 CHEMISTRY 31. Identify reagent (P) and write the structure of products (Q, R, S and T) in the following series of the reac- tions. NH2 NHCOCH3 [P] ClSO3H NH3 [Q] [R] H+/H2O (i) HNO3/H2SO4, 20ºC (ii) H+/H2O, heat [S] [T] (Anitbacterial) 32. For the reaction H3C C2H5 C Br + KOH(aq) C6H5 (dextro) (i) What is the optical activity of the product? (ii) Draw the energy profile for the reaction (iii) Write the structure of hte inermediate (iv) What is the effect of the doubling concentration of KOH on the rate of the products? (v) If aqueous KOH is replaced by alcoholic KOH. Write the structure of the products formed 33. (a) Suggest a method for the following transformation involving minimum number of steps CH3 CH3 NO2 COOH Indicate the reagents/reaction conditions required at each step clearly. (b) A dipeptide on hydrolysis gives two amino acids (X) and (Y). If the dipeptide is first treated with HNO2 and then hydrolysis is carried out, (X) and lactic acid are obtained. (X) on heating gives 2, 5-diketopiperazine as shown below. Identify (X) and (Y), and write their sequence in the dipeptide. H N O O N H 34. Identify the compounds A, B, C, D and E in the following reactions. O H2SO4 (i) OH–, PhCHO [A] C6H5 C CH3 [B] HgSO4 (ii) H+, heat heat NH2NH2/KOH (i) O3 [D] + [E] [C] (ii) Zn/H2O 5 CHEMISTRY 35. (a) Why do the boiling points of the following compounds vary in order, H 2O H 2Se H 2S? (b) Identify the products in the reaction of CCl4 and SiCl4 with water. Justify your answer. 36. (a) Write the steps involved in the production of pure elemental silicon from silica. (b) Both the products A and B, in the following reactions, contain boron and nitrogen. Identify A and B. C6 H5Cl LiAlH4 3NH4Cl 3BCl3 heat A THF B 37. (a) Addition of potassium oxalate solution to a hot solution of potassium dichromate containing dilute sulfuric acid leads to effervescence and formation of potassium trisoxalatohromate (III). (i) Write the chemical formula of the chromium complex formed. (ii) Write the balanced chemical formula for the formation of the complex. (iii) Calculate the room temperature spin-only magnetic moment, in Bohr magnetons, of the complex. (b) Write the structures of possible isomers of CoCl2 en 2 Cl 38. (a) Draw the unit cell of CsCl lattice. Draw the (100) and (110) planes separately and indicate the positions of cesium and chloride ions. (b) The hydration enthalpies of divalent metal ions of ten elements from calcium to zinc are plotted against their atomic numbers. Why do the hydration enthalpies of only three elements Ca, Mn and Zn fall on a straight line, whereas values for other metal ions deviate from this line. 39. (a) 5 grams of a protein was hydrolysed into amino acids, one of which is alanine. To this mixture, 0.1 gram of partially deutrated alanine, H 2 N CH CD3 COOH , was added. After through mixing, some of the alanine was separted and purified by crystallization. The crystalline alanine contains 0.652 weight percent of D. How many grams of alanine were originally present in 5 grams of protein? (b) What is the role of ammoniacal buffer in the volumetric titration of zinc sulphate against EDTA, using Solochrome black (Eriochrome black T) indicator? Write the structure of Zn-EDTA anionic complex. 40. (a) Calculate the pH of a solution obtained by mixing 50.00 mL of 0.20 M weak acid HA (Ka = 10–5) and 50.00 mL of 0.20 M NaOH at room temperature. (b) One mole of a salt of type MX is dissolved in 1.00 Kg of water. The freezing point of the solution is – 2.4ºC. Calculate the percent dissociation of the salt in water. 41. (a) The rate constant of the reaction ClO NO Cl NO 2 varies with temperature as: TK 200 400 k cm 3s1 2.0 1011 1.0 1011 Determine the Arrhenius activation energy of the reaction, assuming that the frequency factor does not change in this temperature range. (b) Ozone seems to be formed in the atmosphere through the photolysis of diatomic molecule: k0 k1 k2 O2 hv 2O ; O O 2 O3 ; O3 O 2O 2 Applying steady-state approximation, determine the rate law for the formation of ozone. Show that the forma- tion of ozone follows first order kinetics when the concentration of O3 is extremely small. 6 CHEMISTRY 42. 2NH 3 is carried out at 300 K by mixing N and H. The standard free (a) The reaction N 2 3H 2 2 2 energy of formation of NH3 is –16.4 kJ/mol. After one hour of mixing, the partial pressures of N2, H2 and NH3 are 50 bars, 2 bars and 200 bars, respectively. What is the reaction free energy at this stage of the reaction? (b) Plot schematically the concentration dependence of molar conductivity of a strong electrolyte and a weak electrolyte in the same figure. The limiting ionic molar conductivities of K+ and Cl– are 73.5 and 76.5 Scm2 mol–1, respectivley. If the molar conductivity of 0.1 M KCl solution is 130.0 S cm2 mol–1, calculate the Kohlrausch’s constant for KCl solution. 43. (a) The electronic wavefunction for hydrogen atom in the 2s state is given as r r 2 exp a0 2a 0 Determine the most probable radial distance for the electron in this state and also the position of the node (in terms of a0). (b) Calculate the wavelength corresponding to the lowest energy excitation of an electron confined to a one- dimensional box of length 1 nm. (Energy levels for a particle in-a-one-dimensional box are given by En = n2h2/8ma2). 44. (a) Solve the differential equation y" 5y ' 6y 0 with the intial conditions y 0 1 and y' 0 0. Here y ' and y" refer to the first and the second derivatives, respectively, of y with respect to x. Verify your answer. (b) For a particle with position r 2iˆ 3jˆ kˆ and momentum p ˆi 2ˆj 2kˆ in m and kg.m.S–1, respec- tively, calculate the magnitude of the angular momentum L r p 7 CHEMISTRY IIT-JAM Chemistry Paper-2007 Instruction: Q.1-30 (Objective questions) carry three marks each and Q.31-44 (Subjective questions) carry fif- teen marks each. 1. The compound, which (i) Reacts rapidly with acetyl chloride (ii) Does not react with 2, 4-dinitrophenylhydrazine and (iii) Does not form a yellow precipitate with excess of iodine in aqueous alkali is (a) Acetone (b) Diethyl ether (c) 2-methyl-2-propanol (d) Ethanol CHO CH2OH H OH H OH 2. H Cl H Cl CH2OH CHO 1 2 The given compounds 1 and 2 are (a) Identical (b) Diastereomeric (c) Enantiomeric (d) Constitutionally isomeric. 3. The correct order of dipole moments of the following componds is: 1. CH 3CH 2CH 2CHO 2. CH 3CH CHCHO 3. CH 3CH 2CH CH 2 (a) 1 2 3 (b) 2 3 1 (c) 3 1 2 (d) 2 1 3 4. Which one of the following compounds gives positive test for both nitrogen and halogen with its Lassaigne’s extract? (a) CH3 NH 2.HCl (b) NH 2OH.HCl (c) NH 4Cl (d) H 2 NNH 2.HCl 5. Which one of the following compounds is optically active? Cl Cl Cl Cl Cl Cl Cl Cl (1) (2) (3) (4) (a) 1 (b) 2 (c) 3 (d) 4 6. The compounds that react with aqueous NaHCO3 to release CO2 are O OH NH HO O HO HO O O N O HOH2C O HO O OH OH HO (2) HO OH (4) (1) (3) (a) 1 and3 (b) 2 and 4 (c) 2 and 3 (d) 1 and 4 1 CHEMISTRY 7. The complementary strand of DNA for the following single stranded DNA sequence, 5' A T C A T G C 3' is: (a) 5' A T C A T G C 3' (b) 5' T A G T A C G 3' (c) 5' G C A T G A T 3' (d) 5' C G T A C T A 3' 8. The value of ‘n’ for the following molecule according to Huckel’s rule is: (a) 16 (b) 4 (c) 3 (d) 14 9. Which one of the following compounds reacts with nitrous acid to give the product [P]? O [P] = H H OH OH (a) (b) NH2 NH2 OH OH (c) (d) NH2 NH2 10. The main product obtained in the following reaction is: O O 1. MeMgBr/dry ether [?] 2. H+/H2O O O O OH (a) (b) O OH O O (c) (d) 11. For a reaction with rate equation –dC/dt = kC2, C0 and C are the concentrations of the reactant at time 0 and t respectively. If 10 minutes were required for C0 to become C0/2, the time required for C0 to become C0/4 is: (a) 10 min (b) 20 min (c) 30 min (d) 40 min. 2 CHEMISTRY 12. For a cyclic process performed by an ideal gas, changes in some thermodynamic functions are zero. Indicate the set in which all the functions are zero. (a) w, E, H, G (b) q, S, H, A (c) q, E, S, G (d) E, S, H, A 13. B. If The plot of Gibb’s free energy G and the extent of a reaction is given below for the reaction A A and B are the chemical potentials of A and B respectively, the INCORRECT statement is: Gibb’s free energy X Z Y 0 Extent of reaction (a) At point X, A B (b) At point Y, G 0 (c) At point Z, A B (d) At equilibrium, the composition of the reaction mixture can be identified. 14. The overlap between the atomic orbitals sketched below is: Z Z Y Y + + – X + X + – – (a) Positive (b) Negative (c) Zero (d) No overalp 15. The pH of a 1.0×10–3 M solution of a weak acid HA is 4.0. The acid dissociation constant Ka is: (a) 1.0×10–3 (b) 1.0×10–4 (c) 1.0×10–5 (d) 2.0×10–5. 16. The normalisation constant ‘A’ for the wavefunction Ae im where 0 2 is: 1 1 (a) (b) 2 (c) 2 (d) 2 2 17. The standard potential of a Daniel cell is +1.10 V and the equilibrium constant for the cell reaction is 1.5×1037. It can be concluded that (a) Zinc oxidises copper (b) Displacement of copper by zinc goes to near completion. (c) Copper oxidises zinc (d) Displacement of zinc by copper goes to completion. 3 CHEMISTRY 18. Which one of the following figures, showing kinetic energy of the ejected electron versus the frequency (v) of the incident photon, represents the Einstein’s photoelectric effect? K.E. (J) K.E. (J) K.E. (J) K.E. (J) (a) (b) (c) (d) v(s–1) v(s–1) 0 v(s–1) 0 v(s–1) 19. An aqueous solution containing 0.01 M FeCl3 and 0.06 M HClO4 has the same ionic strength as a solution of (a) 0.09 M NaCl (b) 0.04 M CuSO4 (c) 0.06 M CuSO4 (d) 0.03 M H3PO4. 20. Which one of the following species is the conjugate base of HO– ? (a) H2O (b) O2 (c) O 2 (d) O32 21. The solid-liquid phase diagram for the Mg-Zn system is shown in the figure below where the vertical line at X(Mg) = 0.33 represents the formation of a congruent melting compound MgZn2. The figure is divided into seven regions depending upon the physical state of the system. The composition of the region #6 represents. 700 600 #1 500 #3 400 #2 #5 #7 300 #4 #6 200 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Zn x(Mg) Mg (a) Single phase of a solution of Mg and Zn (b) Two phase region between the solid Zn and solid MgZn2. (c) Two phase region between the liquid and solid MgZn2. (d) Two phase region between solid Mg and solid MgZn2. 22. In the extraction of metals from their ores, which one of the following reduction methods can bring about a non- spontaneous reduction? (a) Electrolytic reduction (b) Reduction by carbon (c) Reduction by another metal (d) Reduction by hydrogen. 23. The correct order of the ionic radii is: (a) ln 3 Sn 4 Sr 2 Rb (b) Sn 4 ln 3 Sr 2 Rb (c) Rb ln 3 Sr 2 Sn 4 (d) Rb Sr 2 ln 3 Sn 4 4 CHEMISTRY 24. The correct valence shell electronic configuration of the element with atomic number 22 is (a) Ar 4s 2 3d 2 (b) Ar 3d 4 (c) Ar 3d 2 4s 2 (d) Ar 4s 2 4p 2 25. The ligand with only sigma bonding character is: (a) CN (b) CH3 (c) CO (d) NO 26. Which one of the following species is NOT isoelectronic with CO? (a) N2 (b) CN (c) NO (d) O 2 27. During witting reaction, a phosphorus yield gets converted to (a) R 3P (b) R 3P 0 (c) R 3P HOH (d) R 2 P PR 2 28. Which of the following reactions does NOT give H3PO4? (a) Ca 3 PO 4 2 H 2SO 4 (b) P4 O6 H 2O (c) PCl5 H 2O (d) P4S10 H 2O 29. The ionic radii of Ca2+ and F– are 100 pm and 133 pm respectively. The coordination number of Ca2+ in the ionic solid will be (a) 8 (b) 6 (c) 4 (d) 2 30. The shape of CH3 ion is: (a) trigonal planar (b) tetrahedral (c) trigonal pyramidal (d) linear. 31. Identify reagent (P) and write the structure of products (Q, S and T) in the following 1. KMnO4 1. NaOH [Q] C11H12O2 [R] C11H12O2 2. NaIO4 2. H+ 1. CH3MgBr [P] (excess) 2. HBr O NaH [T] [S] C13H19BrO Identify the structures of the intermediate compouds Q, R and S. Show the transformation for each step 5 CHEMISTRY 32. (a) For the following scheme of transforamations, draw the structures of A, B, C and D. CHO H OH HO H phenylhydrazine (3 eq) benzaldehyde (excess) [A] [B] H OH H+ H OH acid catalysed CH2OH rearrangement OH O OH Br2/H2O HIO4 HO [D] [C] HO O (b) Complete hydrolysis of a pentapeptide with 6 N HCl at 110ºC in a sealed tube gave 2 equivalents of glycine, one equivalent each of tyrosine, leucine and phenylalanine. Reaction of the pentapeptide with Sanger’s reagent (2, 4-dinitrofluorobenzene, DNFB) and subsequent hydrolysis gave the DNFB derivative of tyrosine. Chymotrypsin cleavages of this peptide yielded tyrosine, leucine and a tripeptid. Deduce the sequence of the pentapeptide. 33. Complete the following reactions with appropriate structures for E, F, G, H and I. O NaNO2 /HCl Zn/AcOH (a) COOEt [E] [F] CO2Et heat [F] + [G] O alkaline KMnO4 heat, acetophenone (b) [H] [I] N 34. (a) Account for the following transformation with an appropriate mechanism. Give the structure of the Hoffmann exhaustive methylation product of 1, 2-dihydro derivative of [X]. OH N MeO MeO H PCl5 N MeO MeO [X] (b) The optically pure ester [J] is hydrolysed in aqueous acetic acid to form a racemic mixture of cis-4, 4- dimethyl-2-acetoxycyclopentanol [K]. Give a mechanistic explanation to account for the formation of [K] and the observed change in the optical activity. 35. (a) M is a first row transition metal. MCl2 on treatment with aqueous ammonia gives a blue coloured solution 6 CHEMISTRY of complex N. A solution of MCl2 also gives a bright red prcipitate of complex O with ethanoic dimethylglyoxime. (i) Identify M and draw the structure of O. (ii) Determine the hydridisation of M in complex N. (iii) Identify the paramagnetic complex. 3 (b) Cr H 2O 6 gave an absorption at 208 kJ/mol which corresponds to 0. Calculate the crystal field stabilisation energy of this complex in kJ/mol. 36. (a) Consider the ethers H3SiOSiH 3 and H3COCH3. (i) Which ether has more lewis base character? (ii) Which angle [Si–O–Si and C–O–C] is greater? Justify your answer. (b) Starting from SiO2, show how the following polymer is prepared industrially? CH3 Si O n CH3 37. (a) A solution of metal ion M 2 when treated with H2S gas gives a black precipitate A. Precipitate A dissolved in hot concentrated nitric acid to give B along with elemental sulfur. The metal ion solution also gives a white precipitate C with an excess of KI. Write the chemical formulae of A, B, and C (b) Why are potassium permanganate solutions unstable in the presence of Mn2+ ions? In the quantitative estimation of iron present in iron ores dissolved in dilute HCl, titrations with dichromate are preferred over titrations with permanganate. Rationalise. 38. (a) Al2Cl6 and Al 2 Me6 are dimeric in gas phase. Draw their structures. Which compound has more Lewis acid character? Explain. (b) Arrange the halides SnCl2 , PbCl2 ,SiCl2 in increasing order of their stability. Give reasons for your answer. 39. (a) Acidification of an aqueous solution of yellow sodium chromate gives an orange coloured A. A compound solution of A on treatment with concentrated H2SO4 gives a bright orange solid B. Compound A in the pres- ence of concentrated H2SO4 reacts with anion C to give a deep red coloured liquid. Identify A, B and C. 215 (b) 84 PO undergoes an emission to give element X followed by a emission to give element Y. (i) Write the valence shell electronic configuration of Y. (ii) Indicate the groups of the periodic table to which X and Y belong. 40. (a) When an ideal monoatomic gas is expanded from 1.5 bar, 24.8 L and 298 K into an evacuated container, the final volume becomes 49.6 L. Calculate H, S and G for the process. (b) The Maxwell distribution function for the distribution of speeds of molecules in gaseous systems is given by 3 m 2 mc 2 f c 4 c 2 exp 2kT 2kT 1 2kT 2 Show that the most probable speed, cmps m 41. (a) At 600 K and 200 bar, a 1:3 (molar ratio) mixture of A2 and B2 react to form an equilibrium mixture 7 CHEMISTRY containing x AB3 0.60. Assuming ideal gas behaviour, calculate Kp for the reaction 2AB g A 2 g 3B2 g (b) A 50 mL 0.05 M solution of Fe(II) is titrated with 0.05 M solution of Ce(IV) in the presence of dilute H2SO4 at 25ºC. Calculate the equivalence point potential and the equilibrium constant K in terms of log K. 0 0 E Fe3 /Fe2 0.75 V, E Ce4 /Ce2 1.45V 42. (a) The vapour pressure of D2O at 20 ºC is 745 mm Hg. When 15 g of a non-volatile compound is dissolved in 200 g of D2O, the pressure changes to 730 mm Hg. Assuming the applicability of Raoult’s law, calculate the molecular weight of the compound. (b) An enzyme following Michaelis-Menten kinetics was found to have highest activity at 37ºC and pH 7.0. If the maximum velocity Vmax for this enzyme was 2.4×10–4 mol L–1 s–1 with an initial enzyme concentration E 0 2.4 nM , calculate the turnover frequency.. 43. (a) Consider the 4 electrons in cyclobutadiene to be free particles in a 2-dimensional square box of length 2Å. Calculate the wavelength of the electronic transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). Also write down the normalised wavefunctions for the occupied degenerate states. (b) The reaction k1 cis k–1 trans is first order in both directions. At 25ºC, the equilibrium constant (K) of this reaction is 0.40. If 0.115 mol. dm–3 of cis-isomer is allowed to equilibrate, calculate the equilibrium concentration of each isomer. 44. (a) With i, j and k as the unit vectors along, X, Y, Z axes, express the vector, P1P2 in the given figure in terms of the coordinate of P1 and P2. Also determine the dot products of the unit vectors, i, j, k. Z ^ P2(x2, y2, z2) k ^ ^ j i O Y X P1 (x1, y1, z1) (b) Deduce whether the matrices A and B commute or not. 2 1 1 1 A B 0 1 0 1 8 CHEMISTRY IIT-JAM Chemistry Paper-2008 Instruction: Q.1-30 (Objective questions) carry three marks each and Q.31-44 (Subjective questions) carry fif- teen marks each. 1. The correct statement describing the relationship between O O OH R2HC N R2HC N R2C N X O Y O Z O is: (a) X and Y are resonance structures and Z is a tautomer (b) X and Y are tautomers and Z is a resonance structure. (c) X, Y and Z are all resonance structures. (d) X, Y and Z are all tautomers. 2. Among the following, the correct statement concerning the optical activity is: (a) A molecule containing two or more chiral centres is always optically active. (b) A molecule containing just one chiral centre is always optically active (c) A molecule possessing alternating axis of symmetry is optically active. (d) An optically active molecule should have at least one chiral centre. 3. The correct order of acidity among. Me N N N N H H H H H H (i) (ii) (iii) (iv) is: (a) (i) < (ii) < (iii) < (iv) (b) (iv) < (i) < (iii) < (ii) (c) (ii) < (i) < (iii) < (iv) (d) (ii) < (iv) < (i) < (iii) 4. The major product obtained in the following reaction. CH3 CH3 H (i) MeI Ph NMe2 (ii) Ag2O, H2O H (iii) is: H3C CH3 H3C H (a) (b) Ph H Ph CH3 H3C Ph CH2 CH2 Ph H3C (c) (d) H H H H 1 CHEMISTRY 5. The major product of the following reaction CH3 H3C anhyd. AlCl3 H3C + H3C Cl is: CH3 CH3 CH3 (a) CH3 (b) CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH 3 (c) (d) H3C CH3 H3C CH3 6. The major product obtained in the following reaction O K2CO3 OH PhCH2Br OH is: O O OCH2Ph OH (a) (b) OH OCH2Ph O O OCH2Ph OCH2Ph (c) (d) OCH2Ph HO OCH2Ph 7. R–(–)–2–Bromooctane on treatment with aqueous KOH mainly gives 2-octanol that is: (a) Optically active with ‘R’ configuration (b) Optically active with ‘S’ configuration (c) A racemic mixture (d) A meso compound 2 CHEMISTRY 8. The major product obtained in the following reaction OH N H+ OMe is: OMe H H N N (a) (b) O OMe O (c) An equimolar mixture of OMe H H N N + O OMe O OMe (d) N O H 9. The major product obtained in the following reaction Ph H+ Me Me OH is: Ph Ph (a) (b) Me Me Me Me Me Ph (c) Me (d) Me Ph Me 3 CHEMISTRY 10. The products of the following reaction CHO Na18OH 2 are O O 18 (a) HO Na18O (b) H O NaO and and O O 18 (c) NaO H18O (d) H O HO and and 11. When one mole of of ice is converted to water at 0ºC and 1 atm, the work done (1 atm) is: (a) 1.1×10–4 (b) 2.0×10–3 (c) 2.0×10–4 (d) 1.1×10–5. 12. When 100 g of water is reversibly heated from 50ºC to 75ºC at 1 atm, the change in entropy (JK–1) of the universe is: (a) –0.31 (b) 0.31 (c) 0 (d) 3.1 13. For a zero order reaction, units of the rate constant is expressed as (a) M 1s 1 (b) M 0 s 1 (c) M 1s 1 (d) M 0 s0 14. 1×10–6 moles of the enzyme carbonic anhydrase dehydrates H2CO3 to produce 0.6 mol of CO2 per second. The turnover number of the enzyme is: (a) N A 6 105 (b) 1 / 6 105 5 (c) 6 10 / N A (d) 6 105 15. Given that the most probable speed of oxygen gas is 1000 ms–1, the mean/average speed (ms–1) under the same conditions is: (a) 1224 (b) 1128 (c) 886 (d) 816 16. If the electron were spin 3/2 particles, instead of spin 1/2, then the number of electrons that canbe accomodated in a level are (a) 2 (b) 3 (c) 4 (d) 5 17. For a particle in a cubic box, the total number of quantum numbers needed to specify its state are (a) 1 (b) 3 (c) 4 (d) 9 18. The maximum number of phases that can co-exist in equilibrium for a one component system is: (a) 1 (b) 2 (c) 3 (d) 4 19. With increasing pressure, the temperature range over which the liquid state is stable. (a) Decreases (b) Increases (c) Remains constant (d) Decreases till the critical pressure and then increases. 20. The conductance at infinite dilution follows the order (a) Li Na K (b) Na Li K (c) K Li Na (d) K Na Li 4 CHEMISTRY 21. The V-shape of SO2 is due to the presence of (a) Two and one bonds. (b) Two and two bonds. (c) Two bonds and one lone pair of electrons (d) Two and two bonds, and one lone pair of electrons. 22. The correct order of the mean bond energies in the binary hydrides is: (a) CH 4 NH 3 H 2O HF (b) NH 3 CH 4 H 2O HF (c) HF H 2O CH 4 NH 3 (d) HF H 2O NH 3 CH 4 23. In CsCl structure, the number of Cs+ ions that occupy second nearest neighbour locations of a Cs+ ion is: (a) 6 (b) 8 (c) 10 (d) 12 24. In the process 92 230 234 U 90 Th X X is: (a) particle (b) particle (c) emission (d) emission 25. For tetrahedral complexes, which always exhibit high spin states, the maximum CFSE (crystal field stablization energy) is: (a) -8 Dq (b) –12 Dq (c) –16 Dq (d) –20 Dq 26. The most abundant element in earth’s crust is: (a) Aluminium (b) Iron (c) Silicon (d) Oxygen 27. Metal-carbon multiple bonds in metal carbonyl are preferably identified from the stretching frequency of (a) Carbon-oxygen bond (b) Metal-carbon bond (c) Metal-oxygen bond (d) Carbon-carbon bond 28. In general, magntic moment of paramagnetic complexes varies with temperature as (a) T2– (b) T (c) T2 (d) T–1. 29. The compound having an S-S single bond is: (a) H 2 S 2O3 (b) H 2 S 2O4 (c) H 2 S 2O7 (d) H 2 S 2O8 30. In a reaction, Na2 S 2O3 is converted to Na2 S4O6. The equivalent weight of Na2 S2O3 for this reaction is (mol. wt. of Na2S2O3 = M) (a) M (b) M/4 (c) M/2 (d) M/3 31. (a) Identify A, B and C in the following reaction sequence. O Me Me B Me KOH A Me C EtOH Me Me CHO O (b) Identify D in the following reaction and suggest a suitable mechanism for its formation. Me Me H N OH 2 D(C7H9N) HCl O O EtOH 5 CHEMISTRY 32. (a) Explain with the help of mechanisms, the observed stereoselectivity in the following epoxide formation reactions. CH3 CH3 CH3 H3C mCPBA H3C N-bromosuccinimide H3C 30% NaOH(aq). O O (b) Explain on the basis of conformational analysis why (1R, 2S)–1, 2-dimethyl-cyclohexane is optically inactive at room temperature. 33. (a) Identify E, F and G in the following synthetic transformation: O Br2/AcOH NaBH4 (i) G Me E F MeOH (ii) H+ (b) An optically active compound H (C5H6O) on treatment with H2 in the presence of Lindlar’s catayst gave a compound I (C5H8O). Upon hydrogenation with H2 and Pd/C, compound H gave J(C5H12O). Both I and J were found to be optically inactive. Identify H, I and J. 34. (a) A disaccharide K gives a silver mirror with Tollen’s reagent. Treatment of K with MeOH/HCl gives a monometry derivative L, which does not react with Tollen’s reagent. Methylation of K with Me2SO4 and NaOH affords an octamethyl derivative of K, which upon acidic hydrolysis gives a 1:1 mixture of 2, 3, 4, 6- tetra-O-methyl-D-glucose and 2, 3, 4-tri-O-methyl-D-glucose. Disaccharide K is also hydrolysed by the enzyme maltase. Identify K and L with proper stereochemistry. (b) Identify M and N in the following reaction sequence. (i) O3 cat. KCN M N (ii) Zn/AcOH 35. In the following reaction sequnce, identify P, R and S. Suggest suitable mechanism for the conversion of P Q and R S. (i) ( C H 3 C O ) 2 O COOH C H 3C O O N a H 2 , P d /C (i) S O C l 2 P + R S (ii) H M eO H ( ii) A lC l 3 , h e a t Q 36. (a) Consider the reactions. (I) Cr2O72– + H2O2 A room temp. CrO(O2)2 Cr3+ Unstable (II) Cr3+ + H2O2 B Cr2O72– (i) Identify A and B. (ii) What is the role of H2O2 in (I) and how does A favour the formation of Cr3+? (iii) What is the role of H2O2 in (II) and how does B favour the formation CrO42–? (b) With the help of equations, illustrate the role of a cis-1, 2-diol in the titration of boric acid with sodium hydroxide. 6 CHEMISTRY 37. (a) Draw the structure of anionic Ca(II)-EDTA chelate. How many rings are formed in the chelate and specify the number of atoms in each ring? (b) Based on VSEPR theory draw the most stable structure of CIF3 and XEF4. 38. (a) Identify A, B and C in the following reaction scheme C A Colourless solution of complex Blue solution of transition metal salt. H2S H2S No precipitate B Black precipitate (b) From the Ellingham diagram given below, identify the metal oxide that can be reduced at a lower tempera- ture by carbon. Justify. CCO Gº/kJ MgO Mg T1 Q > R (b) Q > P > R (c) Q > R > P (d) R > P > Q 27. The major product formed in the reaction O O HOOC H3C O CH3 H+ HO is: HOOC O O H3C O (a) O O (b) CH3 HO O HOOC HOOC CH3 (c) O (d) HO CH3 HO 28. Arrange the following in the correct order of acidity of the hydrogen indicated in bold. H H H H P Q R (a) P > Q > R (b) R > Q > P (c) Q > R > P (d) P > R > Q 29. Among the following tlhe major product obtained in the reaction below is: CH3 i. NaNH2 ii. CH3Br N CH3 4 CHEMISTRY CH2CH3 CH3 (a) (b) N CH3 N CH2CH3 CH3 CH3 (c) (d) N CH3 H3C N CH3 Br CH3 30. Which of the followng are aromatic? P Q R S (a) P and Q (b) Q and R (c) R and S (d) Q and S 31. (a) A conainer is partitioned into two compatments, one of which contains 2 moles of He while the othercontains 3 moles of Ar. The gases are ideal. The temperature is 300 K and the pressure is 1 bar. R = 0.083 L bar mol–1 K–1, ln (2/5) = –0.92, ln (3/5) = –0.51 (i) What is the total Gibbs free energy of the two gases? (ii) If the partition between the two compartments is removed and the gases are allowed to mix, then what is the Gibbs free energy of the mixture? (iii) What is the change in enthalpy in this process? (b) Obtain (i) the molar heat of formation of CH4(g) and (ii) the average C–H bond energy, to the nearest kilojoule (kJ), from the given data: G kJ mol1 (1) CH 4 g CH 3 g H g 435 (2) CH 3 g CH 2 g H g 444 (3) CH 2 g CH g H g 444 (4) CH g C g H g 339 (5) C graphite C g 717 (6) H 2 g 2H g 436 32. (a) (i) Draw the P-T phase diagram of water. (ii) Label the different regions in this diagram. (iii) On the diagram, show the liquid-vapour equilibrium for a dilute solution of NaCl, with the help of a dashed curve. G T H (b) The temperature dependence of the Gibb’s free energy G is T T 2 P Obtain the expression for the temperature dependence of the equilibrium constant K given that H 0 A BT (Where A and B are constants.) 5 CHEMISTRY 33. (a) In the space provided, plot: (i) Conductometric titration curve of 0.1 M AgNO3 with 1 M NaCl, extended beyond the end point 0 Na 0 Ag Conductance Volume of NaCl solution added (ml) (ii) pH vs. Volume of HCl, for a potentiometric titration of 0.1 (N) NH4OH with 0.1 N HCl. 14 pH 7 Volume of HCl (ml) (iii) Variation of the molar conductivity of NaCl with the square root of its concentration. c (b) The Zn 2 | Zn half cell E 0.762 V is connected to a Cu 2 | Cu halff cell E 0.340 V. What is the value of E cell for spontaneous conversion of chemical energy to electrical energy? What is the value of log10 K , where K is the equilibrium constant? Use (2.303 RT/F) = 0.06. 34. (a) The following initial rate data were obtained for the reaction 2NO g O2 g 2NO 2 g Partial Pressure of Initial rate NO O2 Run1 p NO p O2 v Run 2 2p NO p O2 4v Run 3 p NO 2p O2 2v (i) What is the rate law for this reaction? (ii) One of the mechanisms proposed for this reaction is: k1 NO g O 2 g NO 3 g k 1 6 CHEMISTRY k2 NO3 g NO g 2NO 2 g Obtain the rate law predicted for this mechanism, assuming a stendy state concentration of NO3. (iii) Predict the rate law for this mechanism, if the first equilibrim step is established quickly and the second step is slow. (b) (i) Write the expression for the vibrational contribution to the total energy of CH4(g) at 500 K. All the vibrational modes are active at this temperature. (ii) Calculate the total internal energy of 1 mole of the gas at this temperature R 8.314 J mol1K 1 35. (a) In the Bohr model of a hydrogen-like atom with atomic number Z, The angular momentum of an electron (of mass me and charge e) is a non-zero integral (n) multiple of h / 2 , where h is the Plank’s constant. and The electrostatic attraction exerted by the nucleus on the electron is balanced by the centrifula force experi- enced by the electron. (i) Write mathematical expressions for the above statements. (ii) Hence obtain the expression for the radius r of the Bohr orbit of the electron in terms of e, n, and Z. (b) Complete the following nuclear reactions: 1 (i) 14 4 7 N 2 He 1 H ........ (ii) 73 Li 11H ............. 36. (a) Highly pure nicke metal can be prepared from its sulphide ore via Ni CO 4. Write the chemical equations involved. (b) Addition of excess of aqueous NH3 followed by ethanolic solution of dimethylglyoxime to a dilute aqueous solution of nickel sulphate changes the solution colour from green to blue to red. Write the strucures of the metal complexes corresponding to green, blue and red colours. 37. The element E
