2nd Year Chemistry Chapter 9 Aromatic Hydrocarbons Solution

chemistry 12th notes chapter No 9

1. Which species represents the electrophile in aromatic Nitration:


2. The benzene ring is oxidized to maleic anhydride when strongly heated with:


3. Aromatic compounds burn with sooty flame because:


4. Toluene is called:


5. Which of the following acid can be used as a catalyst in Friedel Craft’s reactions:


6. What is the molecular formula of TNT?


7. Benzene cannot undergo:


8. Which of the following is not an electrophile?


9. Toluene can be converted to benzoic acid in the presence of:


10. The term ‘Aromatic’ was derived from:


11. Molecule of benzene contain


12. Substituted phenyl groups are called:


13. C − H bond lengths in benzene are:


14. Hexanol structure of benzene was confirmed by:


15. When acetylene is heated at 300°C in Cu-tube, the product obtained is:


16. In which compound benzene rings are isolated?


17. The carbon-carbon bond distance in benzene:


18. Which Electrophilic substitution reaction is too vigorous to control:


19. Effect of substituent on benzene ring is due to:


20. Chlorine react with benzene in the presence of sunlight to give:


21. Benzene is prepared from n-Hexane in the presence of which catalyst?


22. Resonance energy of benzene is:


23. Which compound is the most reactive one?


24. A six membered ring containing one double bond is called:


25. The benzene molecule contains:


26. Nitration of Toluene takes place at:


27. Benzene is stable than ethene because it has:


28. Heating a mixture of Sodium benzoate and soda lime gives:


29. The bond angles in benzene ring are:


30. Alkyl benzene are readily oxidized by acidified:


31. The electrophile in aromatic sulphonation is:


32. Sulphuric acid generates nitronium ion by reacting it with:


33. The possible isomers of xylene are:


34. The difference between amount of heat actually released and the experimentally calculated heat is called:


35. Benzene + Ozone →Y, in this sequence Y is:


36. During nitration of benzene, the active nitrating agent is:


37. Presence of double or triple bond is a sign of:


38. Which one of the following species is ortho and para director:


39. Each carbon in benzene ring is ⎯⎯⎯⎯ hybridized:


40. The second substitution in benzene ring would give rise isomeric products:


41. Which class of compound is most reactive:


42. The reaction shown here is:


43. Which compound was recognized as the parent member of aromatic compounds:


44. The three alternate single and double bonds in the benzene ring are called:


45. Cyclic structure of benzene was proposed by:


46. In toluene synthesis by Friedel Craft, the reactants in addition to anhydrous  AlCl₃ are:


47. How many molecules of chlorine add to benzene in the presence of sunlight:


48. The molecular formula of naphthalene is:


49. The C – C bond in benzene is formed by hybridized carbon atom and overlapping is due to:


50. Meta directing groups decrease the ——– of benzene ring:


51. Shape of benzene molecule is:


52. On hydrogenation benzene liberates energy:


53. Aromatic hydrocarbons are derivatives of:


54. Ortho, para derivatives are obtained by halogenations of:


55. Among the following compounds which can be readily sulphonated:


56. The electron releasing effect of Methyl group is significant and it makes the ring a good:


57. The empirical formula of Benzene was determined by:


58. Hybridization of each carbon atom in benzene ring is:


59. This reaction is:


60. Benzene is obtained from Benzene sulphonic acid by treating it with:


61. Benzophenone is also known as:


62. The conversion of n-Hexane into benzene by heating in the presence of Pt is called:


63. Which of the following is ortho and para directing group:


64. Molecular mass of benzene is determined by:


65. Structure of benzene is resonance hybrid of all ⎯⎯⎯⎯ structures:


66. Which one of the following is not monocyclic aromatic hydrocarbon:


67. Which of the following explains the structure of benzene:


68. Amongst the following, the compound that can be most readily sulphonated is:


69. The number of 6-bonds in benzene are:


70. In which of the following cases, the benzene rings are isolated:


71. The carbons in the benzene ring are:


72. Which of the following species participate in Sulphonation of benzene ring:


73. Main source of aromatic compound is:


74. The compound prepared by electrophilic substitution reaction of benzene is:


75. In which one of the following compound rings are not fused together at ortho positions:


76. Most common reactions of benzene and its derivatives are:


77. Which one of the following does not decolorize KMnO₄?


78. Benzene is prepared from Cyclohexane by the process called:


79. Which one of the following is (m-xylene):


80. The stability of aromatic compounds _____ with the increase in the number of its resonance structures:


81. Substitution of halogens in the benzene ring requires which catalyst?


82. All the following are monosubstituted aromatic compounds, except:


83. Benzene was discovered by Michael Faraday’s in:


84. Benzene reacts with ozone and gives:


85. Hydrogen to carbon ratio in aromatic hydrocarbons is:


86. Benzene does not undergo:


87. All are ortho & Para directing groups except:


Short Questions

1. Aqueous solution of CH₃COONa is basic in nature.
2. Aqueous solution of CuSO₄ is acidic in nature. Justify it.
3. Calculate the percentage by weight of NaCl if 2g of it is dissolved in 20g of water.
4. Define Ebullioscopic constant with example.
5. Define molarity and molality.
6. Define upper consulate temperature. Give two examples. Define hydrolysis with example.
7. Define Zeotropic mixtures. Give one example.
8. Depression of freezing point is a colligative property. Justify it.
9. Differentiate between hydration and hydrolysis.
10. Differentiate between ideal and non-ideal solutions.
11. Differentiate between molarity and molality.
12. Give the general mechanism of Friedal Craft’s alkylation?
13. Give the mechanism of nitriation of benzene?
14. Give three examples of condensed aromatic hydrocarbons adn give their names?
15. Give two statements of Raoult’s Law.
16. How benzene can be converted to acetophenone?Give its mechanism;
17. How does ozone affect benzene to give glyoxal?
18. How hexane and heptane can give benzene and toluene respectively?Or What is aromatization?
19. How molality is independent of temperature but molarity depends on temperature?
20. How toluene can be converted to benzoic acid?
21. If the groups like OH⁻ Sh and – NH₂ are present on the benzene ring the ring is activated and ortho para products are obtained. Give reasons?
22. If-COOH or –Cₙ groups are present on the benzene ring they deactivate the ring and meta products are obtained. Give reasons?
23. Justify that boiling points of solvents increase due to presence of non-volatile solutes.
24. Nitration of toluene gives ortho and para nitrotoluene while the bromination of mitrobenzene gives m-bromonitro benzene. Give reasons?
25. One molal solution of glucose is dilute as compared to one molar solution of glucose. Justify it?
26. One molal solution of urea is dilute as compared to one molar solution of urea. Justify it?
27. Prepare maleic acid from benzene?
28. Relative lowering of vapor pressure is independent of temperature. Justify it.
29. There are three alternate double bonds in the bonzene ring but why all the carbon-carbon bonds are equal length?
30. What are major products when chlorine reacts with toluene in the presence of sunlight?
31. What are nonbenzoid aromatic compounds?
32. What are the characteristics of aromatic compounds?
33. What are the names of four major parts of apparatus used in Landsberger’s method for elevation of boiling point?
34. What are those reactions which show that benzene is unsaturated hydro carbon?
35. What are zeotropic and azeotropic mixtures?
36. What do you mean by electrophilic substitution reactions of benzene?Give general mechanism?
37. What do you mean by term aromatic?
38. What happens when benzene is heated with conc.H₂SO₄ at 80 ⁰C?Why oleum is required for the sulphonation of benzene?
39. What informations do we get from X-ray analysis of benzene?
40. What is fractional crystallization?
41. What is meant by molality? Give its formula.
42. What is meant by water of crystallization? Give an example.
43. What is molarity? Calculate the molarity of a solution containing 9g of glucose in 250 cm³ of solution.
44. What is sigma complex and how does it get the stability?
45. What is the role of FeCI₃ and AICI₃ in electrophilic substitution reaction of benzene?
46. What is Wurtz-Fitting reaction?
47. Which orbitals in benzene give stability to benzene but not to alkenes?
48. Why Beckman’s thermometer is used to find the depression in freezing point?
49. Why is the vapor pressure of a solution lesser than vapor pressure of pure solvent?
50. Why NaCl and KNO₃ are used to lower the melting points of ice?
51. Why the solubility of glucose into water increases by increasing temperature?
52. Write down the resonace structures of benzene and indicate their relative contributions towards the actual structure of benzene?
53. Write the reactions which give the evidence for the ring structure of benzene?

Long Questions

1. Explain classification of aromatic hydrocarbons on the basis of number of rings
2. Describe the structure of benzene on the basis of atomic orbital treatment.
3. What is resonance? Explain structure of benzene by method.
4. Write four methods for the preparation of benzene
5. Discuss two industrial and two laboratory methods to prepare benzene.
6. What are Friedel- Crafts reactions? Explain mechanisms of alkylation and acylation of benzene.
“7. What happens when toluene is reacts with:
Cl₂ in the presence of sunlight ii) KMnO₄ in the presence of H₂SO₄”
8. Convert benzene into: (i) Cyclohexane (ii) Maleic acid (iii) Glyoxal (iv) Benzene sulphonic acid.

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