Organic Molecules MCQs [Organic Chemistry]

1. Which statement is true?

(A) Resonance hybrids are inherently unstable

(B) Resonance hybrids are average of all resonance forms resembling the less stable forms

(C) Resonance hybrids are averages of all resonance forms resembling the more stable forms

(D) Resonance hybrids are more stable than any individual resonance form

2. Which of the mentioned statement is false about resonance?

(A) It increases the stability of a molecule

(B) It decreases the reactivity of the molecule

(C) It increases the reactivity of the molecule

(D) It leads to similar type of bonds

3. The greater stability of benzyl carbonium ion as compared to t-butyl carbonium ion is due to

(A) Resonance effect

(B) Electrometric effect

(C) Inductive effect

(D) Steric effect

4. Compounds in which carbons use only sp³ hybrid orbital for bond formation is

(A) HC≡CH

(B) CH₃CH₂CH₃

(C) CH₃ – CH = CH₂

(D) CH=CH–CH₂–CH₃

5. What is the bond angle between hybrid orbitals in methane?

(A) 115.5°

(B) 105.7°

(C) 109.5°

(D) 180°

6. In hydrogen bonding a hydrogen atom is bonded to which of the highly electronegative atoms?

(A) F

(B) O

(C) N, O, F

(D) N

7. Which of the mentioned statements is not true regarding applications of H-bonding?

(A) It explains the usual b.p. and m.p. of certain class of compounds

(B) It explains the solubility of certain organic compounds in hydroxylic solvents

(C) It explains the lack of ideal behavior in gases and solutions

(D) It has strong influence on the configuration of certain molecules

8. The compounds whose formation require a host compound and a guest compound are known as

(A) Exclusion compounds

(B) Crystal compounds

(C) Stoichiometric compounds

(D) Inclusion compounds

9. What is the common host compound for the formation of inclusion compound?

(A) Cholic acid

(B) Thiourea

(C) Urea

(D) All A, B, and C

10. Which of the mentioned order of bond angles is not true?

(A) H₂O < CH₄ < H₂S

(B) H₂S < H₂O < NH₃

(C) H₂O < NH₃ < CH₄

(D) PH₃ < NH₃ < CH₄

11. Which of the mentioned is the true order of bond dipole moment?

C-Br > C-I’)”> (A) C-Cl < C-I < C-Br

C-Br > C-I’)”> (B) C-I > C-Br > C-Cl

C-Br > C-I’)”> (C) C-Br < C-I < C-Cl

C-Br > C-I’)”> (D) C-Cl > C-Br > C-I

12. Which of the mentioned molecule has more dipole moment?

(A) Methane

(B) Chloroform

(C) Toluene

(D) Nitro phenol

13. An induction of dipole or polarity in non-polar bond, and consequent electron shifting along a chain of atoms is known as

(A) Resonance effect

(B) Inductive effect

(C) Hyperconjugation

(D) Stark effect

14. The chemistry of carbon compounds and its derivatives is known as

(A) Physical chemistry

(B) Analytical chemistry

(C) Organic chemistry

(D) Applied chemistry

15. Molecular orbital theory was developed by which of the mentioned scientist?

(A) E. Schrodinger

(B) Pauling

(C) Heitler, London and Pauling

(D) Mulliken, Hund and Huckel

16. Which of the mentioned bonds has least bond energy?

(A) H-bond

(B) Covalent bond

(C) Ionic bond

(D) Coordinate bond

17. The complete transfer of a shared pair of electrons to one of the atoms joined by a double or triple bond at the requirement of an attacking reagent is known as

(A) Hyperconjugation

(B) Resonance effect

(C) Electromeric effect

(D) Inductive effect

18. Which of the mentioned statements is not true regarding electrometric effect?

(A) It precedes a polar addition reaction

(B) It is brought into play instantaneously at the demand of attacking reagent

(C) The original electronic condition is restored after the removal of attacking reagent

(D) It is permanent effect

19. The decrease in electron density at one position accompanied by a corresponding increase at other position is known as

(A) Electromeric effect

(B) Asymmetric effect

(C) Resonance effect

(D) Inductive effect

20. Which of the mentioned statements is not true regarding resonance?

(A) All limiting structures must contribute equally

(B) The limiting structures must have same number of paired and unpaired electrons

(C) The energy of the various limiting structures must be same

(D) The position of atomic nuclei must be same

21. Which of the mentioned statements is not true regarding the important characteristics of aromatic compounds?

(A) They are usually cyclic compounds

(B) They are resistant to usual addition reactions

(C) They are less stable

(D) They usually undergo substitution reactions

22. Inductive effect can be used to explain

(A) Dipole moment of chemical bonds

(B) All A, B, and C

(C) Strength of acids

(D) Strength of bases

23. True order of increasing –I effect of groups is

–CN > –COOH > –F’)”> (A) –CN > –NO₂ > –COOH > –F

–CN > –COOH > –F’)”> (B) –NO₂ > –CN > –COOH > –F

–CN > –COOH > –F’)”> (C) –F > –COOH > –CN > –NO₂

–CN > –COOH > –F’)”> (D) –F > –CN > –NO₂ > –COOH

24. Which of the mentioned case of acid or base strength is not explained by inductive effect?

Trimethyl amine’)”> (A) Dimethyl amine > Trimethyl amine

Trimethyl amine’)”> (B) Formic acid > Acetic acid

Trimethyl amine’)”> (C) Dimethyl amine > Methyl amine

Trimethyl amine’)”> (D) Chloroacetic acid > Acetic acid

25. Which of the mentioned class of compounds follow the criteria of aromaticity?

(A) The compounds must have high degree of unsaturation

(B) They must have cyclic clouds of delocalized (4n + 2)π electrons

(C) They must have the property to undergo addition reactions

(D) They must have the property to undergo substitution reactions

26. How many electrons are present in benzene, naphthalene and anthracene?

(A) 6, 10, 14

(B) 10, 6, 14

(C) 2, 6, 14

(D) 2, 4, 6

27. Which of the mentioned organic molecule is not aromatic?

(A) Anthracene

(B) Naphthalene

(C) Cyclo-octatetraene

(D) Benzene

28. Cyclic polymers of ethylene glycol formed by condensation are known as

(A) Cryptates

(B) Brown ether

(C) Crown ether

(D) Both A and C

29. Compounds consisting of two or more interlocked rings are known as

(A) Catenanes

(B) Inclusion compounds

(C) Cage compounds

(D) Crown ether

30. The most stable carbonium ion is

(A) See butyl

(B) Tert butyl

(C) n-butyl

(D) Isobutyl

31. Each of the following group exerts a +I effect except

(A) CH₃⁺

(B) CH₃

(C) OH⁻

(D) (CH₃)₃C⁻

32. Which of the mentioned compounds has highest dipole moment?

(A) Chloromethane

(B) Dichloromethane

(C) Chloroform

(D) Carbon tetrachloride

33. The delocalization involving C-H sigma bond electrons is known as

(A) Mesomerism

(B) Conjugation

(C) Resonance

(D) Hyperconjugation

34. Which of the mentioned group will have hyperconjugation effect when attached to benzene?

(A) CH(CH₃)₂

(B) CH

(C) CH₃

(D) C.-C(CH₃)₃

35. Which of the mentioned is most basic?

(A) Aniline

(B) Benzylamine

(C) Diphenylamine

(D) N-methylaniline

36. The hybridization of C-atoms in 1, 2-butadiene is

(A) sp, sp², sp³

(B) sp²

(C) sp

(D) sp³

37. Which of the mentioned hybridization results in a linear organic molecule?

(A) sp

(B) sp²

(C) sp³

(D) sp³d

38. Which of the mentioned molecules has shortest C-C bond length?

(A) CH₃–CH₂–CH₃

(B) CH₃C≡CH

(C) CH₃CH=CH₂

(D) CH₂=CH-CH₂-CH₃

39. Which of the mentioned is most acidic?

(A) Phenol

(B) p-nitrophenol

(C) o-Nitrophenol

(D) m-nitrophenol

40. Which of the mentioned effects best explains that o-nitrophenol is insoluble in water?

(A) Inductive effect

(B) Resonance effect

(C) Intermolecular H-bonding

(D) Intramolecular H-bonding

41. Trimethylamine is a weaker base than dimethylamine is explained by

(A) Steric effect

(B) Resonance effect

(C) Inductive effect

(D) Electromeric effect

42. All bond lengths in benzene are identical due to

(A) Hyperconjugation

(B) Inductomeric effect

(C) Electromeric effect

(D) Resonance effect

43. What is the bond length of C=C?

(A) 1.20Å

(B) 1.34Å

(C) 1.54Å

(D) 1.68Å

44. Which of the mentioned hydrocarbons has the shortest C-C bond length?

(A) HC≡CH

(B) CH₂=CH₂

(C) CH₃CH₃

(D) Benzene

45. The carbon-carbon bond strength is maximum in

(A) HC≡CH

(B) CH₂=CH₂

(C) CH₃CH₃

(D) Benzene

46. The criteria for aromaticity is presence of

(A) Presence of 4nπ electrons

(B) Cyclic structure

(C) Unsaturation’s

(D) Presence of 4n + 2π electrons

47. C-O bond lengths in carboxylate anion are equal because of

(A) Resonance effect

(B) Inductive effect

(C) H-bonding

(D) Resonance of identical contributing structures

48. Chlorine when attached to benzene has

(A) +I and +R effect

(B) I and +R effect

(C) +I and -R effect

(D) I and -R effect