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AROMATIC HYDROCARBON

1. The function of anhydrous AlCl3 in the Friedel-Craft's reaction is to
A: To produce electrophile

 

2. Benzene reacts with CH3COCl in the presence of to give
A: C6H5COCH3
Solution:

 

3. Acylation process is preferred than direct alkylation because (by the Friedel-Craft's reaction)
A: In alkylation, polyalkylated product is formed

 

4. Benzene cannot undergo
A: Elimination

 

5. Coaltar is main source of
A: Aromatic compounds
Solution: Coal tar is a main source of aromatic hydrocarbons like benzene, naphthalene, anthracene, phenol etc

 

6. Which of the following is not formed by the ozonolysis of o-xylene
(a) Glyoxal       (b) Ethyl glyoxal       (c) Dimethyl glyoxal      (d) Methyl glyoxal
A: Ethyl glyoxal       

 

7. The number of   and  bonds in a molecule of benzene is
A: 
Solution:


 

8. The ratio of σ and π bonds in benzene is
A: 4
Solution:

 

9. Carbon atoms in benzene molecule is inclined at an angle of
A: 120º

 

10. When benzene is treated with excess of Cl2 in the presence of I2, the end product is
A: Hexachlorobenzene

 

11. Chemical name of the insecticide gammexene is
A: Benzene hexachloride
Solution:


 

12. Gammexane is obtained from benzene when it reacts with
A: Cl2 in bright sunlight (in the absence of a catalyst)

 

13. Point out the wrong statement in relation to the structure of benzene
       (a) It forms only one monosubstitution product
       (b) The C - C bond distance in benzene is uniformly 1.397 Å
       (c) It is a resonance hybrid of a number of canonical forms
       (d) It has three delocalised π - molecular orbitals
A: It forms only one monosubstitution product

 

14. Which equation represents an example of Friedel-Craft's reaction


       
A: (a) 
Solution:  

15. The most stable carbonium ion among the following is


      
A: (a)  
Solution: 

 

16. The reaction of toluene with chlorine in presence of ferric chloride gives predominantly
A: o- and p-chlorotoluenes
Solution:

 

17. The product formed when toluene is heated in light with Cl2 and in absence of halogen carrier is
A: Benzotrichloride
Solution:

 

18. Attacking or reactive or electrophilic species in nitration of benzene is or In the nitration of benzene with concentrated HNO3 and H2SO4 the attack on ring is made by
A: 
Solution:

 

19. Which of the following reactions takes place when a mixture of concentrated HNO3 and H2SO4 reacts on benzene at 350 K
A: Nitration
Solution:

 

20. Nitration of benzene by nitric acid and sulphuric acid is
A: Electrophilic substitution

 

21. Necessary conditions for halogenation are
      (a) Cold and dark                   (b) Presence of halogen carrier
      (c) Both (a) and (b)                (d) None
A: C) Both (a) and (b)  

 

22.  
A: Friedel-Craft's reaction
Solution: 

 

23. The reaction of benzene with chlorine in the presence of iron gives
A: Chlorobenzene
Solution: 


 

24. Benzene was discovered by
A: Faraday

 

25. The correct structure of benzene was proposed by
A: Kekul

 

26. The centric structure of benzene was proposed by
A: Armstrong and Baeyer 

 

27. The bond order of individual carbon-carbon bonds in benzene is
A: Between one and two

 

28. Six carbon atoms of benzene are of
A: One type

 

29. On heating a mixture of sodium benzoate and sodalime, the following is obtained
        (a) Toluene      (b) Phenol     (c) Benzene        (d) Benzoic acid
A: (c) Benzene
Solution:


 

30. Benzene on treatment with a mixture of conc. HNO3 and conc. H2SO4 at 100oC gives
A: m-dinitrobenzene
Solution:

 

31. What is the end product which is obtained on the nitration of toluene
A: 2, 4, 6-trinitrotoluene
Solution:

 

32. Which of the following processes is reversible
       (a) Halogenation      (b) Sulphonation         (c) Nitration     (d) None
A: (b) Sulphonation
Solution:

 

33. The attacking (electrophilic) species in sulphonation of benzene is
A: SO3

 

34. Which xylene is most easily sulphonated
A: Meta
Solution:

m-xylene is most easily sulphonated because O and P both positions are free with respect to methyl group.

 

35. Toluene on oxidation with dilute HNO3 and alkaline KMnO4 gives
A: Benzoic acid
Solution:

 

36. Benzene vapour mixed with air when passed over V2O5 catalyst at 775K gives
A: Maleic anhydride
Solution:

 

37. Most common reactions of benzene (aromatic hydrocarbon) and its derivatives are
A: Electrophilic substitution reactions

 

38. Which is most readily nitrated
(a) Benzene           (b) Phenol          (c) Aniline          (d) Nitrobenzene
A: (b) Phenol
Solution: Phenol is most easily nitrated.

 

39. o, p-directing groups are mostly
A: Activating groups

 

40. Which among the following is the strongest o, p-directing group 
(a) OH        (b) Cl      (c) C6H5        (d) Br
A: (a) OH

 

41. The compound that is most reactive towards electrophilic nitration is
A: Toluene
Solution:

 

42. Amongst the following, the compound that can be most readily sulphonated is
(a) Benzene     (b) Nitrobenzene     (c) Toluene     (d) Chlorobenzene
A: (c) Toluene

 

43. Which of the following would be least reactive towards bromine 
(a) Nitrobenzene     (b) Phenol     (c) Anisole     (d) Chlorobenzene
A: (a) Nitrobenzene
Solution: Nitrobenzene is least reactive towards bromine because of presence of -NO2 group decreases electron density at o and p positions and hence attack of electrophile on the benzene nucleus is difficult because + ve charge on o and p position repel the incoming electrophile.

 

44. Amongst the following, the compound that is nitrated with difficulty is
(a) Benzene     (b) Nitrobenzene    (c) Toluene     (d) Phenol
A: (b) Nitrobenzene 

 

45. Select the true statement about benzene from amongst the following 
       (a) Because of unsaturation benzene easily undergoes addition reactions
       (b) There are two types of C - C bonds in benzene molecule
       (c) There is a cyclic delocalisation of electrons in benzene
       (d) Monosubstitution of benzene group gives three isomeric substances
A: (c) There is a cyclic delocalisation of electrons in benzene

 

46. Anhydrous AlCl3 is used in the Friedel-Craft's reaction because it is
A: Electron deficient
 Solution:  


 

47. (i) Chlorobenzene and (ii) benzene hexachloride are obtained from benzene by the reaction of chlorine, in the presence of
A: (i) Anhydrous and AlCl3 (ii) direct sunlight


48. In Friedel Craft's alkylation, besides AlCl3 the other reactants are
A: 

 

49. Nitration of benzene is a
A: Electrophilic displacement

 

50. Benzene shows
(a) Substitution          (b) Addition         (c) Oxidation      (d) All of these
A: (d) All of these

 

51. Benzene can be obtained in the reaction
A: Trimerisation of ethyne
Solution: Benzene can be obtained by polymerisation of acetylene.

 

52. Thiophene and benzene are separated by
A: Sulphonation of benzene

 

53. Which of the following is a hydrocarbon 
(a) Urea      (b) Benzene      (c) Ammonium cyanate     (d) Phenol
A: Benzene
Solution: Benzene C6H6 is made up of hydrogen and carbon only.     

 

54. Aromatic compounds burn with sooty flame because
A: They have a relatively high percentage of carbon
Solution: They have a relatively high percentage of carbon

 

55. Among the following compound which one is planar in shape 
(a) Methane       (b) Acetylene      (c) Benzene      (d) Isobutane
A: (c) Benzene
Solution: All 6 carbons of Benzene are sp2 -hybridised so it is planar.

 

56. Among the following statements on the nitration of aromatic compounds, the false one is
(a) The rate of nitration of benzene is almost the same as that of hexadeuterobenzene
(b) The rate of nitration of toluene is greater than that of benzene
(c) The rate of nitration of benzene is greater than that of hexadeuterobenzene
(d) Nitration is an electrophilic substitution reaction
A: (c) The rate of nitration of benzene is greater than that of hexadeuterobenzene

 

57. Methyl group attached to benzene can be oxidised to carboxyl group by reacting with
A: KMnO4
Solution:


A: Explosive

Solution: 2, 4, 6 - Trinitro toluene (TNT) is used as explosive.
 

59. The compound ‘A’ when treated with HNO3 (in presence of H2SO4) gives compound ‘B’ which is then reduced with Sn and HCl to aniline. The compound ‘A’ is
A: Benzene
Solution:

 

60. Which is formed when benzene is heated with chlorine in the presence of sunlight
A: C6H6Cl6

 

61. The compound used as an explosive is
A: 2, 4, 6-trinitrotoluene
Solution: TNT is used as an explosive.

 

62. Adding of Cl2 to benzene in the presence of AlCl3 is an example of
A: Substitution
Solution:

 

63. What happens when naphthalene balls are put inside kerosene
A: Dissolves easily

 

64. Three fused benzene rings are found in
A: Anthracene

 

65. Product obtained after nitration of nitrobenzene is
A: 1, 3-dinitrobenzene
Solution:

 

66. After ozonolysis of benzene (not hydrolysis), the product is
A: Benzene triozonide

 

67. Which acid will not form hydrocarbon
A: Picric acid

 

68. Catalytic dehydrogenation of n-haptane in presence of Cr2O3/Al2O3 at 750 K gives
A: toluene
Solution:


A: 3-nitrochlorobenzene
Solution:

 

70. Which of the following has lowest knocking property
(a) Olefins                                     (b) Straight chain paraffins
(c) Aromatic hydrocarbons        (d) Branched chain paraffins
A: (c) Aromatic hydrocarbons

 

71. In which of the following, the bond length between carbon and carbon atom is equal 
(a) 2-butene       (b) Benzene      (c) 1-butene     (d) 1-propyne
A: (b) Benzene
Solution: In benzene due to resonance all the carbon–carbon bond lengths are equal 1.39Aº which is between C- C (1.54Aº) and C- C (1.34Aº)

 

72. Benzene is prepared in laboratory from which one of the following compounds
(a) C6N5N2Cl       (b) C6H5OH    (c) C6H5COONa       (d) C6H5S03H
A: (C) C6H5COONa
Solution:

 

73. Which of the following is not used in Friedel-crafts reaction
(a) Phenyl acetanilide     (b) Bromobenzene     (c) Benzene     (d) Chlorobenzene
A: (a) Phenyl acetanilide   
Solution: Friedel-Craft’s reaction involves the introduction of an alkyl or acyl group into benzene ring in the presence of a catalyst. The presence of an electron withdrawing group in the ring hinders the reaction. Therefore phenyl acetanilide is not used. 

 

74. In chlorination of benzene, the reactive species is
A: Cl+
Solution: Halogenation is initiated by free redical.

 

75. Which of following having delocalised electron
(a) Benzene      (b) Cyclohexane            (c) CH4              (d) C2H6
A: (a) Benzene

 

76. Benzene molecule is
A: Planar
Solution: In benzene all the six carbon atoms are present in the same plane. All the carbon atoms are sp2 hybridized. Hence, it is a planar molecule.

 

77. Pyridine is less basic than triethylamine because
A: In pyridine, lone pair of nitrogen is delocalized
Solution: Basicity of amines is due to availability of an unshared pair (lone pair) of electrons on nitrogen. This lone pair of electrons is available for the formation of a new bond with a proton or Lewis acid.
Pyridine is less basic than triethylamine because lone pair of nitrogen in pyridine is delocalised.

 

78. Electrophile in the case of chlorination of benzene in the presence of FeCl3 is
A: Cl+
Solution: In chlorination electrophile is Cl+ (chloronium ions).

 

79.  Which one of the following will undergo meta substitution on monochlorination 
(a) Ethoxy ethane     (b) Chlorobenzene    (c) Ethyl benzoate       (d) Phenol
A: (c) Ethyl benzoate   
Solution:     

 

80. Nitration of toluene takes place at
A: Both o- and p-positions
Solution:

 

81. Which of the following is not o, p—directing group
(a) -NH2              (b) -OH           (c) -X (halogens)           (d) -CHO
A: (d) - CHO
Solution:

Presence of - CHO decrease electron density at o to p positions. Hence, attack of an electrophile occurs at m-position. therefore it is meta directing group.

 

 

82. Benzene can react with
A: HNO3

 

83. The compound ‘A’ having formula C8H10 (aromatic) which gives 1 mononitro substitute and 3 nitrosubstitute compound is
A: p-Xylene

 

84. Catalytic hydrogenation of benzene gives
A: Cyclohexane
Solution:

 

85. Benzene is obtained from
A: Coaltar

 

86. The ‘middle oil’ fraction of coaltar distillation contains
A: Naphthalene

 

87. Lindane can be obtained by reaction of benzene with
A: Cl2/Sunlight
Solution:

 

88. Which of the following oil is obtained from benzene after fractional distillation of coaltar 
(a) Light oil        (b) Heavy oil         (c) Middle oil          (d) Anthracene oil
A: (a) Light oil
Solution: Benzene on fractional distillation gives light oil [It is lighter than water and hence called as light oil]

 

89. Hydrocarbon C6H6 decolourise Br2 water and gives ppt. with ammonical AgNO3 Hydrocarbon can be
(a) 1, 3, 5 Cyclohexatriene      (b) 1, 5 Hexadiyne         (c) 2, 4 Hexadiyne        (d) None
A: (d) None
Solution: Because Ammonical  AgNO3 reduce  C  CH bond of yne.

 

90. Decreasing order of C-C bond length is
(i) C2H4      (ii) C2H2     (iii) C6H6    (iv) C2H6
(a) IV > III > I > II                  (b) I > II > IV > III
(c) II > I > IV > III                  (d) IV > I > III > II
A: (a) IV > III > I > II
Solution:


                 

 

91. Benzene can be obtained by heating either benzoic acid with X or phenol with Y. X and Y are respectively 
(a) Zinc dust and soda lime                      (b) Soda lime and zinc dust
(c) Zinc dust and sodium hydroxide       (d) Soda lime and copper
A: (b) Soda lime and zinc dust

Solution:

 

92. Order of reactivity of C2H6, C2H4 and C2H2 is
A: C2H2 > C2H4 > C2H6
Solution: Unsaturated hydrocarbons are more reactive than saturated hydrocarbons. Among ethyne C2H2 and ethene C2H4 the later is more reactive as C  C triple bond is quite strong bond and therefore ethyne generally require catalysts (like Hg2+ etc) in its reactions.

 

93. Which of the following yield both alkane and alkene
(a) Kolbe’s reaction      (b) Williamson’s synthesis  
(c) Wurtz reaction        (d) Sandmeyer reaction
A: (a) Kolbe’s reaction

Solution: Kolbe’s methods – Electrolysis of a concentrated aqueous solution of either sodium or potassium salts of saturated mono carboxylic acids yields higher alkanes at anode.

 

94. Aromatisation of n-heptane by passing over (Al2O3 + Cr2O3) catalyst at 773 K gives
A: Toluene
Solution:

 

95. Amongst the following the most basic compound is
(a) Benzylamine     (b) Aniline     (c) Acetanilide    (d) p-nitroaniline
A: a (Benzylamine)
Solution: -NH2 group is not linked with benzene ring.

 

96. When toluene is treated with KMnO4, what is produced
A:  Benzoic Acid
Solution:

 

97. In presence of light and heat toluene chlorinated & react with aqueous NaOH to give
A: Benzoic Acid
Solution:

Posted Date : 19-02-2021

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