AIEEE 2010 Solved Questions Paper Chemistry

AIEEE 2001 25044­1 Question & Solutions ­ wwww prernaclasses.com AIEEE 2010 Chemistry Solution PART B Chemmistr 31. In aqueous solution the ionization constants for carbonic acid are K 1 = 4.2 × 10 –7 and K 2 = 4.8 × 10 –11 Select the correct statement for a saturated 0.034 M solution of the carbonic acid. (1) The concentration of H + is double that of CO 3 2– (2) The concentration of CO 3 2– is 0.034 M (3) The concentration of CO 3 2– is greater than that of HCO 3 – (4) The cencentrations of H + and HCO 3 – are approximately equal 31. (4) Since second dissociation is less therefore [H + ] » [HCO 3 – ] 32. Solubility product of silver bromide is 5.0 ×10 –13 . The quantity of potassium bromide (molar mass taken as 120 g mol –1 ) to be added to 1 litre of 0.05 M solution of silver nitrate to start the preciptation of AgBr is (1) 5.0 ×10 –8 g (2) 1.2 × 10 –10 g (3) 1.2 ×10 –9 g (4) 6.2 × 10 –5 g 32. (3) [Br – ] = (5 ×10 –13 ) /(0.05) = 10 –11 M = [KBr] amount = 1.2 × 10 –9 g 33. The correct sequence which shows decreasing order of the ionic radii of the elements is (1) O 2– > F – > Na + > Mg 2+ > Al 3+ (2) Al 3+ > Mg 2+ > Na + > F – > O 2– (3) Na + > Mg 2+ > Al 3+ > O 2– > F – (4) Na + > F – > Mg 2+ > O 2– > Al 3+ 33. (1) For isoelectronic ions, greater is the positive charge smaller is the size and greater is the negative charge larger is the size. 34. In the chemical reactions, the compounds ‘A’ and ‘B’ respectively are (1) Nitrobenzene and Chlorobenzene (2) Nitrobenzene and fluorobenzene (3) Phenol and benzene (4) Benzene diazonium chloride and fluorobenzene 34. (4) N2 + Cl -(A) ¾ ¾ ¾ ® ¾ 4 HBF F R Prerna Tower, Road No 22 Contractors Area, Bistupur, Jamshedpur 8311001 Tel ­0657)2221892, www.prernaclasses.comAIEEE 2001 25044­1 Question & Solutions ­ wwww prernaclasses.com 35. If 10 –4 dm 3 of water is introduced into a 1.0 dm 3 flask at 300 K, how many moles of water are in the vapour phase when equilibrium is established ? (Given : Vapour pressure of H 2 O at 300 K is 3170 Pa ; R = 8.314 J K –1 mol –1 ) (1) 1.27 × 10 –3 mol (2) 5.56 × 10 –3 mol (C) 1.53 × 10 –2 mol (4) 4.46 × 10 –2 mol 35. (1) Amount of H 2 O = 10 –4 ×10 3 = 0.1 ml = 0.1 gm. V = 1000 ml. T = 300K, P = 0.03170 atm n = (PV /RT) = (0.03170 ×1) /(0.082 × 300) = 1.27 ×10 –3 mol 36. From amongst the following alcohols the one that would react fastest with conc. HCl and anhydrous ZnCl 2 , is (1) 1Buttano (2) 2Buttano (3) 2Methylprropan­2­o (4) 2Methylppropano 36. (3) Greater the stability of carbocation, greater is the rate of reaction. (3) gives 3º carbocation. 37. If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water (DT f ), when 0.01 mol of sodium sulphate is dissolved in 1 kg of water, is (K f = 1.86 K kg mol –1 ) (1) 0.0186 K (2) 0.0372 K (3) 0.0558 K (4) 0.0744 K 37. (3) DT f = 1.86 × (0.01 /1) × 3 = 0.0558 (K) 38. Three reactions involving H 2 PO 4 – are given below : (i) H 3 PO 4 + H 2 O ® H 3 O + + H 2 PO 4 – (ii) H 2 PO 4 – + H 2 O ® HPO 4 2– + H 3 O + (iii) H 2 PO 4 – + OH – ® H 3 PO 4 + O 2– In which of the above does H 2 PO 4 – act as an acid ? (1) (i) only (2) (ii) only (3) (i) and (ii) (4) (iii) only 38. (2) In (ii) H 2 PO 4 – acts as acid. 39. The main product of the following reaction is C 6 H 5 CH 2 CH(OH)CH(CH 3 ) 2 ¾ ¾ ¾ ¾ ¾ ® ¾ 4 2 SO H conc. (1) (2) (3) (4) 39. (2) Ph – CH 2 –CH(OH)–CH(CH 3 ) 2 ¾ ¾ ¾ ¾ ¾ ® ¾ 4 2 SO H conc. PhCH=CH(CH 3 ) 2 Benzyl carbocation is more stable and trans alkene is the most stable product. Also there is conjugation in the product.AIEEE 2001 25044­1 Question & Solutions ­ wwww prernaclasses.com 40. The energy required to break one mole of Cl – Cl bonds in Cl 2 is 242 kJ mol –1 .The longest wavelength of light capable of breaking a single Cl – Cl bond is (c = 3 ×10 8 ms –1 and N A = 6.02 ×10 23 mol –1 ) (1) 494 nm (B) 594 nm (C) 640 nm (D) 700 nm 40. (1) B.E. per molecule = (242 ×1000) /(6.02 × 10 23 ) = (6.6 ×10 –34 ×3×10 8 ) /l \ l = 494 nm 41. 29.5 mg of an organic compound containing nitrogen was digested according to Kjeldahl’s method and the evolved ammonia was absorbed in 20 mL of 0.1 M HCl solution. The excess of the acid required 15 mL of 0.1 M NaOH solution for complete neutralization. The percentage of nitrogen in the compound is (1) 29.5 (2) 59.0 (3) 47.4 (D) 23.7 41. (4) meq. of NH 3 = 20 × 0.1 ×1 – 15 × 0.1 ×1 = 0.5 meq. \ % of N = (0.5 ×14 ×100 ×1000) /(1000 × 29.5) = 23.7 % 42. Ionisaion energy of He + is 19.6 ×10 –18 J atom –1 . The energy of the first stationary state (n = 1) of Li 2+ is (1) 8.82 × 10 –17 J atom –1 (2) 4.41 ×10 –16 J atom –1 (3) –4.41 × 10 –17 J atom –1 (4) –2.2 × 10 –15 J atom –1 42. (3) E 1 /E 2 = (Z 1 22 × n 2 2 ) /(n 1 2 × Z 2 2 ) or 19.6 ×10 –18 /x = 4 /9 or x = 4.41 × 10 –17 43. On mixing, heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components (heptane and octane) are 105 kPa and 45 kPa respectively. Vapour pressure of the solution obtained by mixing 25.0 g of heptane and 35 g of octane will be (molar mass of heptane = 100 g mol –1 and of octane = 114 g mol –1 ) (1) 144.5 kPa (2) 72.0 kPa (3) 36.1 kPa (4) 96.2 kPa 43. (2) n H = (25 /100) = 0.25 ; n O = 35 /114 = 0.3 ; X H = 5 /11 and X O = 6 /11 \ P T = (5 /11) ×105 + (6 /11) × 45 = 72 44. Which one of the following has an optical isomer ? (A) [Zn(en) 2 ] 2+ (2) [Zn(en)(NH 3 ) 2 ] 2+ (3) [Co(en) 3 ] 3+ (4) [Co(H 2 O) 4 (en)] 3+ (en = ethylenediamine) 44. (3) [Co(en) 3 ] 3+ is optically active. 45. Consider the following bromides : The correct order of S N 1 reactivity is (1) A > B > C (2) B > C > A (3) B > A > C (4) C > B > A 45. (2) Rate of S N 1 reaction depends on stability of carbocation intermediate. B gives allyl, C gives 2º and A gives 1º carbocation.AIEEE 2001 25044­1 Question & Solutions ­ wwww prernaclasses.com 46. One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is (1) Ethene (2) Propene (3) 1butten (4) 2butten 46. (4) CH 3 – CH = CH – CH 3 ¾ ¾ ¾ ¾ ¾ ® ¾ Ozonolysis 2CH 3 – CHO 47. Consider the reaction : Cl 2 (aq) + H 2 S (aq) ® S (s) + 2H + (aq) + 2Cl – (aq) The rate equation for this reaction is rate = k [Cl 2 ] [H 2 S] Which of these mechanisms is/are consistent with this rate equation ? A. Cl 2 + H 2 S ® H + + Cl – + Cl + + HS – (slow) Cl + + HS – ® H + + Cl – + S (fast) B. H 2 SÛH + + HS – (fast equilibrium) Cl 2 + HS – ® 2Cl – + H + + S (slow) (1) A only (2) B only (3) Both A and B (4) Neither A nor B 47. (1) Rate = K [Cl 2 ][HS – ] ; K eq = [H + ][HS – ] /[H 2 S] \ [HS – ] = K eq [H 2 S] /[H+] \ Rate = K [Cl 2 ] × K eq [H 2 S] /[H+] So, B is not the correct mechanism. 48. The Gibbs energy for the decomposition of Al 2 O 3 at 500 ºC is as follows : (2 /3) Al 2 O 3 ®(4/3) Al + O 2 , D r G = + 966 kJ mol –1 The potential difference needed for electrolytic reduction of Al 2 O 3 at 500 ºC is at least (1) 5.0 V (2) 4.5 V (3) 3.0 V (4) 2.5 V 48. (4) DG = –nFE or 966000 = 4 × 96500 × E \ E = 2.5 V 49. The correct order of increasing basicity of the given conjugate bases (R = CH 3 )is (1) R H N C HC O RCO < < º < 2 (2) 2 H N R C HC O RCO < < º < (3) 2 H N O RCO C HC R < < º < (4) R C HC H N O RCO < º < < 2 49. (1) order of acidic strength is RCOOH > HC ºCH > NH 3 > R–H So, basicity of their conjugate base will have opposite order. 50. The edge length of a face centered cubic cell of an ionic substance is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is (1) 144 pm (2) 288 pm (3) 398 pm (4) 618 pm 50. (1) a = 2r + +2r – Þ 508 = 2 × 110 + 2 x \ x = 144 51. Out of the following, the alkene that exhibits optical isomerism is (1) 2methyl­22­penten (2) 3methyl­22­penten (3) 4methyl­11­penten (4) 3methyl­11­penten 51. (4) CH 3 –CH 2 –CH(CH 3 )–CH=CH 2 is optically active.AIEEE 2001 25044­1 Question & Solutions ­ wwww prernaclasses.com 52. For a particular reversible reaction at temperature T, DH and DS were found to be both +ve. If T e is the temperature at equilibrium, the reaction would be spontaneous when (1) T = T e (2) T e > T (3) T > T e (4) T e is 5 times T 52. (3) DG = DH – TDS \ T > T e as DG is negative for spontaneous reaction. 53. Percentages of free space in cubic close packed structure and in body centered packed structuur are respectively (1) 48% and 26% (2) 30% and 26% (3) 26% and 32% (4) 32% and 48% 53. (3) P.F. of CCP is 74% and that of BCC is 68% 54. The polymer containing strong intermolecular forces e.g. hydrogen bonding, is (1) natural rubber (2) teflon (3) nylon 6,6 (4) polystyrene 54. (3) Nylon 6,6 is a fibre which has H–bonding. 55. At 25 o C, the solubility product of Mg(OH) 2 is 1.0 x 10 11 . At which pH, will Mg 2+ ions start precipitattin in the form of Mg(OH) 2 from a solution of 0.001 M Mg 2+ ions ? (1) 8 (2) 9 (3) 10 (4) 11 55. (3) [OH – ] 2 = 10 –11 /10 –3 = 10 –8 \ [OH – ] = 10 –4 p OH = 4 ; p H = 10 56. The correct order of E º M 2+ /M values with negative sign for the four successive elements Cr, Mn, Fe and Co is (1) Cr > Mn > Fe > Co (2) Mn > Cr > Fe > Co (3) Cr > Fe > Mn > Co (4) Fe > Mn > Cr > Co 56. (2) Based on fact. 57. Biuret test is not given by (1) proteins (2) carbohydrates (3) polypeptides (4) urea 57. (2) Biurate test is not given by carbohydrate as it does not contain N. 58. The time for half life period of a certain reaction A®Products is 1 hour. When the initial concentraatio of the reactant ‘A’, is 2.0 mol L –1 , how much time does it take for its concentration to come from 0.50 to 0.25 mol L –1 if it is a zero order reaction ? (1) 1 h (2) 4 h (3) 0.5 h (4) 0.25 h 58. (4) t 1/2 = (2–1) /K or K = 1 \ t 1/2 = (0.5 – 0.25) /1 = 0.25 hr. 59. A solution containing 2.675 g of CoCl 3 . 6 NH 3 ( molar mass = 267.5 g mol –1 ) is passed through a cation exchanger. The chloride ions obtained in solution were treated with excess of AgNO 3 to give 4.78 g of AgCl ( molar mass = 143.5 g mol –1 ). The formula of the complex is ( At. mass of Ag = 108 u ) (1) [CoCl(NH 3 ) 5 ]Cl 2 (2) [Co(NH 3 ) 6 ]Cl 3 (3) [CoCl 2 (NH 3 ) 4 ]Cl (4) [CoCl 3 (NH 3 ) 3 ] 59. (2) n AgCl = 4.78 /143.5 = 0.03 and n complex = 0.01. Therefore 3 moles of AgCl are produced per mole of complex. Therefore formula is [Co(NH 3 ) 6 ]Cl 3AIEEE 2001 25044­1 Question & Solutions ­ wwww prernaclasses.com 60. The standard enthalpy of formation of NH 3 is – 46.0 kJ mol –1 . If the enthalpy of formation of H 2 from its atoms is – 436 kJ mol –1 and that of N 2 is – 712 kJ mol –1 , the average bond enthalpy of N – H bond in NH 3 is (1) – 1102 kJ mol –1 (2) – 964 kJ mol –1 (3) + 352 kJ mol –1 (4) + 1056 kJ mol –1 60. (3) N 2 + 3H 2 ® 2NH 3 –46 × 2 = –6x + (3 × 436 + 712) or –92 = – 6x + 2020 \ x = 352