Chemistry-4.Work Book (Phase - IV)

Work Book (Phase - IV) Subjective: Board Type Questions 1. Which bond is more polar in the following pairs of molecules? (a) H3C – H, H3C – Br (b) H3C – NH2, H3C – OH (c) H3C – OH, H3C – SH 2. Write resonance structures of (a) CH3COO– and (b) C6H5NH2. Show the movement of electrons by curved arrows. 3. Write the resonance structures of CH2 = CH – CHO and arrange them in order of decreasing stability. 4. Give reasons why the following two structures (I and II) cannot be the major contributors to the real structure of CH3COOCH3. 5. Using curved arrow notation, show the formation of reactive intermediates when the following covalent bonds undergo heterolytic cleavage. (a) CH3 – SH (b) CH3 – CN (c) CH3 – Cu 6. Giving proper justification, categories the following molecules/ions as nucleophile or electrophile: 7. Identify the electrophilic centres in the following: CH2 = C = O, CH3CN, CH3I 8. What is the relationship between the members of following pairs of structures? Are they identical, structural or geometrical isomers, or resonance contributors? (a) (b) (c) (d) 9. What type of aromatic compounds are present as particulates in the air? 10. Why ‘photochemical smog’ is so called? 11. Draw the structure of the tautomer of phenol and write its IUPAC name. 12. Arrange the following in increasing order of C – C bond length: C2H6, C2H4, C2H2. 13. Name the alkyl groups derived from isobutene. 14. Select electrophiles out of the following: H+, Na+, Cl–, C2H5OH, AlCl3, SO3, CN–, 15. Arrange the following: (i) in order of increasing stability. (ii) in order of decreasing stability. (iii) in order of increasing stability. 16. Which is expected to be more stable, O2NCH2CH2O– or CH3CH2O– and why? 17. Indicate - and -bonds in the following compounds: (a) C6H6 (b) C6H12 (c) CH2Cl2 (d) CH2 = C = CH2 (e) CH3NO2 (f) HCONHCH3 18. A hydrocarbon has the molecular mass 70. Write all the possible structural isomers and give their IUPAC names. 19. What is the nature of ‘photochemical smog’? 20. Explain inductive and electromeric effect with examples. 21. Explain hyperconjugation effect. 22. What is COD? Which chemical substance is generally used in its measurement? 23. For the following bond cleavages, use curved arrows to show the electron flow and classify each as homolysis or heterolysis. Identify reactive intermediate products as free radical, carbocation and carbanion. (a) (b) (c) (d) 24. Draw the resonance structures of the following carbocation? Use curved arrows to show how one structure is converted into another. 25. (a) Write the resonance structures of diazomethane (CH2N2). (b) Give the hybridized state of carbon and each N in each structure. (c) How does the H – C – H bond angle in the hybrid compare with the bond angles predicted from each contributing structure? 26. With proper justification, arrange the following in order of increasing stability. 27. Give the IUPAC name for the amine. 28. Write resonance structures of the given compound. 29. trans-pent-2-ene is polar while trans-but-2-ene is non-polar. Explain. 30. Starting with acetylene, how will you prepare pentan-2-one? 31. Acetylene reacts with dil. H2SO4 in presence of mercury salts to give acetaldehyde but with dil. HCl under similar conditions, it gives vinyl chloride. Explain why? 32. Draw the structures of the following showing all C and H atoms. (a) 2-methyl-3-isopropylheptane (b) Dicyclopropylmethane 33. Arrange the following in increasing order of their release of energy on combustion. (i) (ii) (iii) (iv) 34. Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile, E+. (i) Chlorobenzene, 2, 4-dinitrochlorobenzene, p-nitrochlorobenzene (ii) toluene, p-H3C – C6H4 – CH3, p-H3C – C6H4 – NO2, p-O2N – C6H4 – NO2. 35. Which of the following shows geometrical isomerism? (i) CHCl = CHCl (ii) CH2 = CCl2 (iii) CCl2 = CHCl 36. A compound is formed by the substitution of two chlorine atoms for two hydrogen atoms in propane. What is the number of structural isomers possible? Fill in the blanks 37. Out of three isomers of C5H¬12, ……………..has the highest boiling point while……………has the lowest boiling point. 38. Out of cis-2-butene and trans-2-butne, …………………..has lower melting point. 39. A four – carbon alkyne having weakly acidic character is……………………. 40. Alkanes undergo…………………reactions whereas alkyes gives………………reactions. IIT Level Questions 41. 42. Predict the major and minor product with reason 43. Use Markovnikov’s rule to predict the product of the following reactions: (i) HCl with CH3CCl = CH2 and (ii) HCl with CH3CH = C(CH3)2. 44. Arrange the following: HCl, HBr, HI, HF in order of decreasing reactivity towards alkenes. 45. Give the structure of an alkene (C4H8) which when treated with H2O/H2SO4 gives C4H10O which cannot be resolved into optical isomers. 46. How will you demonstrate that double bonds of benzene are somewhat different from that of olefines? 47. Write the ozonolysis products of (i) mesitylene (ii) o-xylene. 48. An organic compound C¬8H18 on monochlorination gives a single monochloride. Write the structure of the hydrocarbon. 49. Which of the following has larger dipole moment? Explain. 1-butyne or 1-butene. 50. State whether true or false: Photobromination of 2 – methylbutane gives a mixture of 1- bromo-2-methyl propane & 2 – methylpropane in the ratio 9:1. Objective: Multiple choice questions with single correct options 1. The condition that cannot be applied for the interconversion of geometrical isomers is (A) heat (B) pressure (C) ultraviolet rays (D) catalysis 2. The maximum number of isomers for an alkene with the molecular formula C4H8 is (A) 2 (B) 3 (C) 4 (D) 5 3. Keto–enol tautomerism is observed in (A) (B) (C) (D) None of the above 4. The two isomers given below are (A) enantiomers (B) diastereomers (C) regiomers (D) position isomers 5. This reaction is leading to % racemization equal to (A) 40 (B) 60 (C) 80 (D) 20 6. But-2-ene exhibit cis–trans isomerism due to (A) Rotation around C3–C4 sigma bond (B) Restricted rotation around C=C bond (C) Rotation about C1–C2 bond (D) Rotation around C2–C3 double bond 7. C2 is rotated anti-clockwise 120°about C¬2–C3 bond. The resulting conformer is (A) partially eclipsed (B) eclipsed (C) gauche (D) staggered 8. Which of the following compound will exhibit cis–trans (geometrical) isomerism? (A) 2-butene (B) 2-butyne (C) 2-butanol (D) Butanal 9. The number of isomers of dibromo derivative (molar mass 186 gmol-1) of an alkene is (A) two (B) three (C) four (D) six 10. The amount of optical rotation does not depend on the (A) concentration of the solution (B) wavelength of the colour of the solution (C) temperature (D) length of the column transversed 11. Which of the following does not posses any element of symmetry? (A) Ethane (B) (+)–Tartaric acid (C) Carbon tetrachloride (D) Meso–tartaric acid 12. Which of the following is the uppermost region of atmosphere? (A) Stratosphere (B) Troposphere (C) Mesosphere (D) Exosphere 13. Which of the following compound will show geometrical isomerism? 1. 2-Butene 2. Propene 3. 1-Phenylpropene 4. 2-Methylbut-2-ene (A) 1, 2 (B) 3, 4 (C) 1, 2, 3 (D) 1,3 14. An organic molecule necessarily shows optical activity if it (A) contains asymmetric carbon atoms (B) is non-planar (C) is non-superimposable on its mirror image (D) is superimposable on its mirror image 15. Which of the following ketone cannot produce oximes that can be geometrical isomers? (A) Acetophenone (B) Methyl ethyl ketone (C) Benzophenone (D) Ethyl isopropyl ketone 16. Which one of the following hydrocarbons has the lowest dipole moment? (A) (B) (C) (D) 17. Which of the following statement is correct? (A) Metamerism belongs to the category of structural isomerism. (B) Tautomeric structures are the resonating structures of a molecule. (C) The violet colouration produced by a molecule with neutral ferric chloride solution indicates the presence of keto group in the molecule. (D) Geometrical isomerism is shown only by alkenes. 18. The optically active tartaric acid is named as D (+) tartaric acid because it has a positive (A) optical rotation and is derived from D glucose (B) pH in an organic solvent (C) optical rotation and is derived from D (+) glyceraldehyde (D) optical rotation only when substituted by deuterium 19. An enantiomerically pure acid is treated with racemic mixture of an alcohol having one chiral carbon. The ester formed will be (A) optically active mixture (B) pure enantiomer (C) meso compound (D) racemic mixture 20. Which of the following statement is correct? (A) Allyl carbonium ion (CH2=CH– ) is more stable than propyl carbonium ion. (B) Propyl carbonium ion is more stable than allyl carbonium ion. (C) Both are equally stable. (D) None of the above 21. Which of the following species is most stable? (A) (B) (C) (D) 22. Which is the strongest carboxylic acid among the following? (A) Cl3CCO2H (B) Br3CCO2H (C) F3CCO2H (D) Cl2CHCO2H 23. The compound with the most acidic hydrogen is (A) CH3CHO (B) CH3COCH3 (C) CH3 CH2CHO (D) CH3COCH2CO2CH3 24. Which of the following is easily debrominated? (A) (B) (C) (D) 25. Which carbocation is most stable? (A) (B) (C) (D) 26. The order of the basicity among the amines is (A) I NH2 > HCºC > OH (B) HCºC->CH3CH2 >NH2 >OH (C) OH>NH2>HCºC>CH3CH2 (D) NH2 >HCºC >OH >CH3CH2 28. Aniline is a weaker base than ethylamine. This is due to (A) I effect of NH2 in aniline (B) M effect of NH2 in aniline (C) +I effect of NH2 in aniline (D) + M effect of NH2 in aniline 29. In the above compound which is true for basic strength of nitrogen marked as ‘a’ and ‘b’ (A) a = b (B) b > a (C) a >b (D) cannot be correlated 30. Safe alternative of CFC is (A) HCFC (B) HCFC-14 (C) HFA142b (D) All of these 31. The possible mechanism of addition reaction between ethene and bromine in non-polar medium would be (A) free radical addition (B) carbene addition (C) electrophilic addition (D) nucleophilic addition 32. The molecule in which distance between the two adjacent carbon atoms is largest is (A) ethane (B) ethene (C) ethyne (D) benzene 33. Among the following which is the strongest base (A) (B) (C) (D) 34. Which one of the following is least acidic? (A) (B) (C) (D ) 35. . Only one structure of B is possible (A), (B) and (C) are (A) (B) (C) both are correct (D) none is correct 36. CH2 = CH – CH = CH2 A and B are (A) CH3 – CH2 – CH = CH2, (CH3CH2COOH + CO2) (B) CH3 – CH = CH – CH3, CH3COOH (2 mol) (C) CH3 – CH = CH – CH3, CH3CHO (2 mol) (D) CH3 – CH2 – CH = CH2, (CH3CH2CHO + HCHO) 37. Which of the following alkene has the lowest heat of hydrogenation? (A) (B) (C) (D) 38. Which is true about this reaction? (A) A is meso 1, 2-butan-di-ol formed by syn addition (B) A is meso 1, 2-butan-di-ol fomred by anti addition (C) A is a racemic mixture of d and l, 1, 2-butan-di-ol formed by anti addition (D) A is a racemic mixture of d and l 1, 2-butan-di-ol formed by syn addition 39. Which of the following will be the correct product (P) of the reaction (A) (B) (C) (D) 40. (A) (B) (C) (D) 41. trans A Which is true statement? (A) A is formed by anti addition and is meso (B) A is formed by syn addition and is meso (C) A is formed by anti addition and is racemic (D) A is formed by syn addition and is racemic 42. In the reaction sequence CH3 CH2 will be (A) 2-methl propane (B) 2- methyl propanone (C) 2- methyl -2- propanol (D) 2- methyl propanal 43. Consider the reaction: The product P is: (A) (B) (C) An equi molecular mixture of (A) and (B) (D) 44. A and B are (A) (B) (C) (D) 45. Which of the following will undergo faster dehydro-bromination? (A) (B) (C) (D) 46. (A) (B) (C) (D) 47. Identify the reagent from the following list which can easily distinguish between 1-butyne and 2-butyne. (A) bromine, CCl¬4 (B) H2, Lindlar catalyst (C) dilute H2SO4, HgSO4 (D) ammoniacal Cu2Cl2 solution 48. Which of the following hydrocarbons has the lowest dipole moment? (A) (B) CH3CºCCH3 (C) CH3CH2CºCH (D) CH2=CH—CºCH 49. The reaction of propene with HOCl proceeds via the addition of (A) H+ in the first step (B) Cl+ in the first step (C) OH– in the first step (D) Cl+ and OH– in a single step 50. In the presence of peroxide, hydrogen chloride and hydrogen iodide do not give anti-Markonikov’s addition to alkenes because (A) both are highly ionic (B) one is oxidizing and the other is reducing (C) one of the steps is endothermic in both the cases (D) all the steps are exothermic in both the cases 51. (A) (B) (C) (D) 52. (A) (B) (C) (D) None of these Multiple choice questions with more than one option correct 53. The gas is/are involved in the formation of photochemical smog (A) CO2 (B) SO2 (C) NO (D) Hydrocarbons 54. Of the following compounds, which will have zero dipole moment? (A) 1, 1-dichloro ethylene (B) cis-1, 2-dichloro ethylene (C) trans-1, 2-dichloro ethylene (D) benzene 55. Which of the following do not represent the first number of their homologous series? (A) CH3OH (B) CH3Cl (C) CH3CN (D) CH3COOH 56. The molecules that will have dipole moment are: (A) 2, 2-dimethylpropane (B) cis-3-hexene (C) 2, 2, 3, 3-tetramethylbutane (D) trans-2-pentene 57. The formula C4H11N represents: (A) four p-amines (B) three s-amines (C) two s-amines (D) one t-amine 58. Keto-enol tautomerism is observed in: (A) (B) (C) (D) 59. Only two isomeric monochloro derivatives are possible for: (A) n-butane (B) 2, 4-dimethyl pentane (C) benzene (D) 2-methyl propane 60. The molecules which exhibit metamerism: (A) C4H10O (ether) (B) C4H8 (alkene) (C) C5H10O (ketone) (D) C4H11N (amine) 61. Isomers will have similar: (A) structural formula (B) molecular mass (C) molecular formula (D) chemical and physical properties 62. Which of the following statements is/are incorrect regarding two organic compounds A and B which are stereoisomers? (A) they must be enantiomers (B) they must be geometrical isomers (C) they can be diastereomers (D) they can be meso compounds 63. Reforming is the process used for (A) preparation of hydrocarbon (B) increasing the octane number (C) preparation of straight chain (D) preparation of 64. The compound (s) which will give propylene on dehydration with conc. H2SO¬4 at 440 K are (A) isobutyl alcohol (B) n-propyl alcohol (C) isopropyl alcohol (D) n-butyl alcohol 65. Which of the following alkynes show acidic character? (A) (B) (C) (D) 66. Grignard reagent gives alkane with (A) C2H5OH (B) HOH (C) NH3 (D) C2H5NH¬2 67. Both methane & ethane may be obtained by one step reaction from (A) CH3I (B) CH3COOK (C) H2C = CH2 (D) CH3MgBr 68. CnH2nO is the general formula of (A) aldehydes (B) ketones (C) unsaturated alcohols (D) unsaturated acids 69. Which of the following do not represented the first number of their homologous series? (A) CH3OH (B) CH3Cl (C) CH3CN (D) CH3COOH 70. The molecules that will have dipole moment are (A) 2, 2 – dimethyl propane (B) cis-3-hexane (C) 2, 2, 3, 3 – tetramethyl butane (D) trans-2-pentene 71. The name is (A) methyl isocyanide (B) methyl carbylamine (C) acetoisonitrile (D) methylisonitrile 72. Cis-2-butene & trans-2-butene are (A) geometrical isomers (B) diasteromers (C) enantiomers (D) position isomers 73. Which of the following can exist in ‘syn & ‘anti’ form? (A) (B) (C) (D) 74. The 2-isomer among the following are (A) I (B) II (C) III (D) IV 75. Keto – enol tautomerism is observed in (A) C2H5CHO (B) C6H5COCH3 (C) C6H5COC6H5 (D) C6H5COCH2COCH3 76. Which of the following statement (s) is/are correct about tautomers? (A) they posses different electronic & atomic arrangements (B) They posses different electronic but same atomic arrangement (C) The have different atomic arrangements but same electronic arrangement (D) They exist in equilibrium Comprehension - I Read the paragraph carefully and answer the following questions: Pyridine like benzene, has six -electrons in delocalized -orbitals, but unlike benzene the orbitals will be deformed as electrons are more attracted towards the nitrogen atom because of its high electronegativity. This is reflected in the dipole of pyridine which has the negative end on N and the positive end on the nucleus. Pyridine is thus referred to as a -deficient heterocycle. By analogy with a benzene ring that carries an electron withdrawing substituent, NO2, one would expect it to be deactivated towards electrophilic attack with the help of -delocalized molecular orbital. We can compare the respective properties of benzene, pyridine, pyrrole, furan and thiophene which very frequently give aromatic electrophilic and nucleophilic substitution reactions in different positions. 77. Arrange the following in increasing order of aromatic character. (A) (i) > (v) > (iv) > (iii) > (ii) (B) (v) > (iv) > (iii) > (ii) > (i) (C) (ii) > (i) > (v) > (iv) > (iii) (D) (i) > (v) > (ii) > (iv) > (iii) 78. Assertion: Dipole moment of pyridine is greater than pyrrole but in opposite direction. Reason: In pyrrole, N atom contributes two electrons for delocalized -orbital but this is not true for pyridine. (A) Assertion is correct but not reason. (B) Assertion and reason both are correct. (C) Assertion and reason both are false. (D) Assertion is wrong but not reason. 79. Electrophilic attack is very difficult for pyridine, but at which position it is relatively easy? (A) Only 2 (B) Only 4 (C) Only 3 (D) 2 and 4 both 80. Identify the product, (P). (A) (B) (C) (D) All of the above Comprehension-II Read the paragraph carefully and answer the following questions: The dehydration of alcohols and the conversion of alcohols to alkyl halides by treatment of hydrogen halides are similar in two important ways: 1. Both reactions are protonated by acids. 2. The reactivity of alcohols decrease in the order, tertiary > secondary > primary. It is due to the formation of stable carbocations, which is stabilized by hyperconjugation and +I effect. These common features suggest that carbocations are key intermediates in alcohol dehydration. It follows three steps mechanism for acid catalysed dehydration of least stable tertiary butyl alcohol. The overall reaction is In step I, protonation of tert-butyl alcohol takes place. In step II, dissociation of tert-butyloxenium ion takes place followed by formation of carbocation. Alkene is formed in step III by deprotonation of tert-butyl cation. 81. What will be the order of rearrangement takes place in case of dehydration of alcohols? (A) Phenyl > alkyl > hydride (B) Hydride > phenyl > alkyl (C) Phenyl > hydride > alkyl (D) Alkyl > hydride > phenyl 82. Why dehydration of vinyl alcohol is not difficult? (A) Due to high enthalpy of vinylic –C–OH bond. (B) Due to unstable nature of =C–OH bond by tautomerism (C) Carbocation never forms in case of vinyl alcohol (D) A and B are correct 83. (A) (B) (C) (D) 84. Which carbocation will not form an intermediate? (A) (B) (C) (D) Comprehension-III Alkene can be oxidised in presence of different reagent to give different product. Alkene on oxidation in presence of silver at high temperature give cyclic ether which also be synthesis by using per acids. Alkene on reductive ozonolysis gives carbonyl compound in presence of zinc and peroxide. On reaction with acidic KMnO4 it also produce corresponding carbonyl compound. Alkyne also oxidised in presence of such reagent but the products are different. Read the above paragraph carefully and give the answer of following questions: 85. Cyclohexene is allowed to reacts with ozone and subsequently with H2O2 and water. The product formed is: (A) Oxylic acid (B) Malenic acid (C) Succinic acid (D) Adipic acid 86. Ethene on reaction with MCPBA in CH2Cl2 forms a compound (A) which on reaction with CH3–MgI and subsequent hydrolysis gives a compound (B). (A) and (B) are respectively (A) (B) (C) (D) 87. An open chain hydrocarbon C7H12 on ozonolysis produces propanone, methanol and 2–oxopropanal. The hydrocarbon could be: (A) (B) (C) Either of these (D) Neither of these 88. A hydrocarbon C8H16 on oxidation with a hot acidified solution of KMnO4 forms 2–butanone and isobutyric acid. The hydrocarbon is (A) (B) (C) (D) Comprehension – IV Reaction intermediates are generated by breaking of covalent bond of the substrate. They are short lived species and are highly reactive. There are six important types of reaction intermediates–carbocation, carbanion, free radical, carbene, benzyne and nitrene. Carbon atom bearing six electrons in its outermost orbit and has a positive charge is called carbocation. Stability of alkyl carbocations can be explained by Inductive effect and hyperconjugation. Anion of carbon is known as carbanion, it carries three bond pairs and one lone pair, thus making the carbon atom negatively charged. Stability of carbanions may be explained by electronegativity of carbanionic carbon, inductive effect and by resonance. Carbon free radicals are odd electron species in which carbon atom bears the odd electron. Stability of alkyl free radicals can be explained by hyperconjugation and number of resonating structures due to hyperconjugation. 89. Consider the following carbocations. (1) (2) (3) (4) Stability of these carbocation in decreasing order is: (A) (4) > (3) > (1) > (2) (B) (4) > (3) > (2) > (1) (C) (3) > (4) > (2) > (1) (D) (3) > (4) > (1) > (2) 90. Stability of given free radicals in decreasing order is (1) (2) (3) (4) (A) (3) > (4) > (1) > (2) (B) (1) > (2) > (3) > (4) (C) (3) > (2) > (4) > (1) (D) (3) > (2) > (1) > (4) 91. For the following reactions: (1) (2) (3) (4) The correct decreasing order of enthalpies of formation of carbocation is: (A) (B) (C) (D) 92. Which allylic carbocation is the most stable carbocation? (A) ( (B) (C) (D) All have same stability Match the following 93. Match the following List – I and List – II. List-I (Groups) List-II (Characteristics) (a) R (p) +Inductive (b) Cl (q)  Mesomeric (c) NH2 (r) Deactivating (d) NO2 (s) Activating 94. Match the following List – I and List – II. List-I (Reactions) List-II (Reagents) (a) (p) Br2 water (b) (q) N – bromosuccinimide (c) (r) HBr (peroxide) (d) (s) HBr (aqueous) 95. Match the following List – I and List – II. List-I (Reactions) List-II (Reagents) (a) Cyclopropane (p) Non-planar (b) Cyclobutane (r) Planar (c) Cyclopentane (r) Least stable cycloalkane (d) Cyclohexane (s) Shows conformations 96. Match the following List – I and List – II. List-I (Compounds) List-II (Properties) (a) CH2 = CH2 (p) Do not show geometrical isomerism (b) (q) Reacts with HBr according to Markownikoff’s rule (c) (r) Symmetrical molecule (d) (s) Decolourise Bayer’s reagent ANSWERS TO WORK BOOK Objective: Single Correct Questions 1. B 2. D 3. B 4. B 5. C 6. B 7. C 8. A 9. B 10. C 11. B 12. D 13. D 14. C 15. C 16. B 17. A 18. C 19. B 20. A 21. D 22. C 23. C 24. B 25. D 26. A 27. B 28. D 29. B 30. D 31. A 32. A 33. A 34. A 35. A 36. B 37. B 38. A 39. B 40. A 41. A 42. A 43. C 44. D 45. D 46. A 47. D 48. B 49. B 50. C 51. C 52. A Multiple Correct Questions 53. A, C 54. C, D 55. C, D 56. B, D 57. A, B, D 58. B, D 59. A, D 60. A, C, D 61. B, C 62. A, B 63. A, B 64. B, C 65. A, B, C 66. A, B, C, D 67. A, B 68. A, B, C 69. C, D 70. B, D 71. A, B, C 72. A, B 73. A, B, C 74. A, C 75. B, D 76. A, D Comprehension 77. A 78. B 79. C 80. D 81. C 82. D 83. D 84. C 85. D 86. C 87. C 88. D 89. A 90. D 91. C 92. B Match the following 93. (a)-(p, s); (b)-(r); (c)-(s); (d)-(q, r) 94. (a)-(s); (b)-(r); (c)-(q); (d)-(p) 95. (a)-(q, r); (b)-(q); (c)-(q); (d)-(p, s) 96. (a)-(p, s, r); (b)-(r, s); (c)-(s); (d)-(p, q, s)