12th Class Chemistry Mcqs With Answers Chapter 9| 2nd Year chemistry mcqs with answers pdf

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12th Class Chemistry Mcqs With Answers Chapter 1


Chapter No 9

Hydrocarbons

1. Which of the following acid can be used as a catalyst in Friedel Crafts  reaction choose which one is correct:

  1. AlCl3
  2. HNO3
  3. BeCl2
  4. NaCl

2. During nitration of benzene, the active nitrating agent is choose which one is correct:

  1. NO3
  2. NO+2
  3. NO2
  4. HNO3

3. The electrophile in aromatic sulphonation is choose which one is correct:

  1. H2SO4
  2. HSO4
  3. SO+3
  4. SO3

4. Hydrogen to carbon ratio in aromatic hydrocarbons is choose which one is correct:

  1. Low
  2. High
  3. Equal
  4. None

5. The second substitution in benzene ring would give rise isomeric products choose which one is correct:

  1. One
  2. Two
  3. Three
  4. Four

6. Molecular mass of benzene is determined by choose which one is correct:

  1. Vapour density method
  2. X-ray diffraction
  3. Elemental analysis
  4. Degradation method

7. C H bond lengths in benzene are choose which one is correct:

  1. 0.99 Å
  2. 1.09 Å
  3. 1.12 Å
  4. 1.397 Å

8. Each carbon in benzene ring is ⎯⎯⎯⎯ hybridized choose which one is correct:

  1. sp
  2. sp2
  3. Sp3
  4. None of these

9. On hydrogenation benzene liberates energy choose which one is correct:

  1. 358.5 kJ/mole
  2. 119 kJ-mol−1
  3. 208 kJ-mol−1
  4. 150.5 kJ-mol−1

10. The benzene ring is oxidized to maleic anhydride when strongly heated with choose which one is correct:

  1. Ni/200°C
  2. V2O5/450°C
  3. AlCl3/150°C
  4. Sunlight

11. Main source of aromatic compound is choose which one is correct:

  1. Petroleum
  2. Coal-tar
  3. Living organism
  4. Dead marine animals

12. When acetylene is heated at 300°C in Cu-tube, the product obtained is choose which one is correct:

  1. Benzene
  2. Thiophene
  3. Divinyl acetylene
  4. Xylene

13. Which one of the following species is ortho and para director choose which one is correct:

  1. CHO
  2. −SO3H
  3. −NO2
  4. Cl

14. The carbon-carbon bond distance in benzene choose which one is correct:

  1. 1.54°A
  2. 1.34°A
  3. 1.2°A
  4. 1.39°A

15. In toluene synthesis by Friedel Craft, the reactants in addition to anhydrous  AlCl3 are choose which one is correct:

  1. C6H6 + CH4
  2. C6H5Cl
  3. C6H6 + CH3Cl
  4. C6H5Cl + CH4

16. Benzophenone is also known as choose which one is correct:

  1. Biphenyl
  2. Dimethyl Ketone
  3. Diphenyl Ketone
  4. Methylphenyl Ketone

17. The no. of possible isomers of xylene are choose which one is correct:

  1. 2
  2. 3
  3. 4
  4. 5

18. The molecular formula of naphthalene is choose which one is correct:

  1. C10H8
  2. C10H10
  3. C10H12
  4. C12H12

19. Chlorine react with benzene in the presence of sunlight to give choose which one is correct:

  1. Chlorobenzene
  2. Benzoyl chloride
  3. Ortho-para dichlorobenzene
  4. Hexachlorobenzene

20. Effect of substituent on benzene ring is due to choose which one is correct:

  1. Resonance
  2. Inductive effect
  3. Both A.  and (b)
  4. Unpredictable

21. In which of the following cases, the benzene rings are isolated choose which one is correct:

  1. Naphthalene
  2. Phenanthrene
  3. Anthracene
  4. Triphenylmethane

22. Benzene is stable than ethene because it has choose which one is correct:

  1. More π-bonds
  2. Localized π-electrons
  3. Delocalized π-electrons
  4. More σ-bonds

23. Which of the following is ortho and para directing group choose which one is correct:

  1. −OH
  2. −OCH3
  3. −CHO
  4. −NH2

24. Among the following compounds which can be readily sulphonated choose which one is correct:

  1. Phenol
  2. Benzene
  3. Nitrobenzene
  4. Chlorobenzene

25. Structure of benzene is resonance hybrid of all ⎯⎯⎯⎯ structures choose which one is correct:

  1. 3
  2. 4
  3. 5
  4. 6

26. Aromatic hydrocarbons are derivatives of choose which one is correct:

  1. Paraffins
  2. Alkene
  3. Benzene
  4. Cyclohexane

27. Which of the following explains the structure of benzene choose which one is correct:

  1. Atomic orbital treatment of benzene
  2. Resonance method
  3. Both A.  and (b)
  4. None

28. The conversion of n-hexane into benzene by heating in the presence of  (Al2O3 + SiO2 + Cr2O3) is called choose which one is correct:

  1. Isomerization
  2. Aromatization
  3. Dealkylation
  4. Rearrangement

29. Toluene can be converted to benzoic acid in the presence of choose which one is correct:

  1. dil. NaOH
  2. dil. HNO3
  3. Conc. HNO3
  4. Acidified KMnO4

30. Cyclic structure of benzene was proposed by choose which one is correct:

  1. Dewar
  2. Faraday
  3. Down
  4. Kekule

31. Benzene does not undergo choose which one is correct:

  1. Addition
  2. Substitution
  3. Polymerization
  4. Aromatization