MCQ on Organic Chemistry No. 2

Test-Organic ChemistryQuestions: 1. Which one of the compounds behaves as an electrophile as well as nucleophile? (a) Acetone (b) Cyanide ion (c) Nitrite ion (d) Sulphite 2. Which one of the nitrogen containing compounds is an electrophile? 3. Consider the following species Arrange these nucleophilic species in their decreasing order of nucleophilicity: (a) 3 > 4 > 2 > 1 (b) 2 > 1 > 3 > 4 (c) 1 > 2 > 3 > 4 (d) 3 > 1 > 2 > 4 4. Benzene gives electrophilic substitution reaction because benzene is (a) aromatic compounds (b) a nucleophile (c) an electrophile (d) a nucleophile and stabilized by resonance 5. Alkenes give electrophilic addition reaction in the pressure of polar protic solvent with those reagents which on dissocation give electrophile and nucleophile. Which reagent will not give addition reaction with alkines. (a) HCl (b) H2SO4 (c) HOCl (d) NaCl 6. Acyl cation has resonating structure (I) and (II): (a) (I) is more stable than (II) (b) (II) is more stable than (I) (c) Stability of (I) and (II) will be the same. (d) For some time (I) will be more stable and for remaining time (II) will be more stable 7. Tautomerism is shown by: 8. Which one of the following compounds has maximum enol content in solution: 9. Which one of the following compounds will not show tautomerism? 10. Arrange basicity of the following compounds in decreasing order: (1) (2) (3) (4) (a) 1 > 4 > 3 > 2 (b) 4 > 1 > 2 > 3 (c) 1 > 4 > 2 > 3 (d) 4 > 2 > 3 > 1 11. Arrange given compounds in order of decreasing acidity: (a) 4 > 2 > 1 > 3 (b) 4 > 2 > 3 > 1 (c) 3 > 1 > 2 > 4 (d) 3 > 1 > 4 > 2 12. +R power of the given group (1) (2) –NH2 (3) –OH (4) –NHCOCH3 in decreasing order is: (a) 1 > 2 > 3 > 4 (b) 4 > 3 > 2 > 1 (c) 1 > 3 > 2 > 4 (d) 1 > 4 > 3 . 2 13. Arrange the following groups in order of decreasing –R (or -M) power (1) NO2 (2) SO3H (3) CF3 (4) CHO (a) 1 > 3 > 2 > 4 (b) 4 > 3 > 2 > 1 (c) 1 > 3 > 2 > 4 (d) 1 > 4 > 3 > 2 14. Which one of the following statements is not correct for electrophilie: (a) Electron deficient species are electrophile (b) Electrophiles are Lewis acids (c) All +ive charged species are electrophiles (d) AlCl3, SF6, IF7 and SO3 are electrophiles. 15. Which one of the following statements are correct for nucleophiles: (a) All negatively charged species are nucleophile (b) Nucleophiles are Lewis bases (c) Alkenes, alkynes benzene and pyrrole are nucleophiles (d) All are correct. 16. Which one of the following is a sec-allylic carbocation: 17. Which allylic carbonation is the most stable carbocation: (a) (b) 18. Secondary force present in the compound are (a) van der Waals attractions (b) Dipole-Dipole attractions (c) Hydrogen bonding (d) All of these 19. Magnitude of van der Waals depends on: (a) Molecular mass of the compound, i.e., number of electrons in the molecule (b) Surface area of the compound (c) Symmetry of the molecule (d) All of these 20. For which carboxylic acid, the pKa value is the lowest: (a) (b) (c) (d) CH2=CH-COOH 21. How many and bonds are present in methyl acrylate: (a) (b) (c) (d) 22. In which of the following molecules carbon does not involve sp3 hybridisation: (a) CH2Cl2 (b) CH2N2 (c) CH2F2 (d) CF2Cl2 23. Dipole moment of p-nitroaniline when copared to nitrobenzene (X) and aniline (Y) will be: (a) Greater than (X) and (Y) (b) Smaller than (X) and (Y) (c) Greater than (X) and smaller then (y) (d) Equal to zero 24. Which of the following resonance structures is the major contributor to the resonance hybrid? (a) I (b) II (c) both have equal contribution (d) They are not resonance structures 25. Rank the following free radicals in order of decreasing stability: (a) I > II > III > IV > V > VI (b) VI > V > IV > III > II > I (c) I > II > IV > VI > III >V (d) I > IV > VI > V > II > III 26. What is the correct decreasing order of reactivity of the following carbonyl compounds in nucleophilic addition reaction: (I) CH3 CHO (II) C6H5CHO (III) HCHO (IV) C6H5CH2CHO (a) III > IV > I > II (b) IV > III > I > II (c) I > IV > III > I (d) II > IV > III > I 27. Which of the following halides undergo solvolysis most easily: (a) C6H5CH2Cl (b) CH2=CH-CH2Cl (c) CH2=CH-CHCl-CH3 (d) (C6H5)3CCl 28. The heat of hydrogenation of benzene is -51.0 Kcal/mole. If heat of hydrogenation of cyclohexadiene and cyclohexene is -58 Kcal / mole and -29 Kcal /mole respectively, what is the resonance energy of benzene: (a) 29 Kcal / mole (b) 36 Kcal / mole (c) 58 Kcal / mole (d) 7 Kcal / mole 29. Most acidic hydrogen is present in : 30. Which one of the following chlorides gives white precipitate with AgNO3 most readily: (a) CH2 = CH-CH2Cl (b) CH2CH-Cl (c) CH3-CH2-CH2Cl (d) (C6H5)2CH-Cl 31. For the following reactions: The correct decreasing order of enthalpies of formation of carbocation is: 32. Which nitrogen in LSD is most basic: (a) 1 (b) 2 (c) 3 (d) all are equally basic 33. Which are the radical reaction? (a) only 1 (b) 1 and 3 (c) 1 and 2 (d) 1, 2 and 4 34. Which among the following statements are correct? (1) Energy needed for hemolytic bond fission is less than that required for the heterolytic bond fission (2) Homolytic bond fission gives neutral species which is paramagnetic in character. (3) Energy needed fror heterolytic bond fission is less than required fro the hemolytic bond fission. (4) Heterolytic bond fission takes place in non polar solvents. 35. Consider the following carbanions: Correct order of stability of these carbanions in decreasing order is: (a) I > II > III (b) III > II > I (c) I > III > II (d) III > I > II 36. Which one of the following carbocations is most stable? (a) (b) (c) (d) 37. Which free radical is the most stable: 38. Which carbocation is the most stable: 39. Which one of the following is most stable? 40. Arrange stability of the given carbocations in decreasing order: (a) I > II > III > IV (b) III > II > I > IV (c) IV > I > II > III (d) II > III > I > IV 41. In which compound delocalization is not possible: (a) 2-butene (b) 1, 3-butadiene (c) 1, 3, 5-hexatriene (d) Benzene 42. Which among the given compounds is most stable? (a) 1-butene (b) 2, 3-dimethy-2-butene (c) cis-2-butene (d) trans-2-butene 43. Of these compounds which compound has minimum heat of hydrogenation? (a) Cis-2-butene (b) Trans-2-butene (c) 2, 3-dimethl-2-butene (d) Benzene 44. Which statement is correct for inductive effect: (a) It is permanent effect (b) It is the property of single bond (c) It causes permanent polarization in the molecule (d) All are correct 45. Consider the following compound: carbon-carbon bond length between C2 and C3 will be: (a) 1.54 (b) 1.3 (c) Less than 1.54 and greater than 1.33 (d) 1.21 46. Consider the following three halides: (1) CH3 – CH2 – Cl (2) CH2 = CH – Cl (3) C6H5 – Cl Arrange C – Cl bond length of these compounds in decreasing order: (a) 1 > 2 > 3 (b) 1 > 3 > 2 (c) 3 > 2 > 1 (d) 2 > 3 > 2 47. Consider the following compounds: Arrange these compounds in decreasing order of their basicity: (a) 1 > 2 > 3 > 4 (b) 2 > 3 > 1 > 4 (c) 4 > 1 > 3 > 2 (d) 4 > 1 > 2 > 3 48. Which one of the following is most basic: 49. C, C double bond length is minimum in: (a) CH3 – CH = CH2 (b) CH2Cl – CH = CH2 (c) CCl3 – CH = CH2 (d) CCl3 – CH = CH – CCl3 50. Which of these species are electrophiles: (a) CO2 (b) CCl4 (c) AlCl3 (d) All of these ******* Answers: Keys: 1 a 2 c 3 a 3 a 4 d 5 b 6 d 7 d 8 d 9 a 10 a 11 a 12 a 13 a 14 c 15 d 16 d 17 c 18 d 19 d 20 b 21 a 22 b 23 c 24 b 25 c 26 a 27 d 28 b 29 a 30 d 31 c 32 b 33 b 34 c 35 b 36 d 37 a 38 b 39 a 40 b 41 a 42 b 43 d 44 d 45 c 46 a 47 c 48 c 49 a 50 d 1 *** Mrs. Shallu Aggarwal Mobile #. 98786-08983 ***