Organic chemistry -MCQS: 1. Bonding molecular orbitals are formed by: A) Destructive overlap B) Constructive overlap C) Repulsion D) Parallel orbitals Answer: B 2. A sigma bond is formed by: A) Sidewise overlap B) Head-on overlap C) d-orbital overlap D) π-overlap Answer: B 3. Which molecule contains only sigma bonds? A) Ethane B) Ethene C) Benzene D) Ethyne Answer: A 4. Non-bonding orbitals contain: A) No electrons B) π electrons C) Lone pair electrons D) Free radicals Answer: C 5. Antibonding orbitals are represented by: A) π B) σ C) σ* D) ππ Answer: C 6. Carbon in methane (CH₄) is: A) sp B) sp² C) sp³ D) dsp² Answer: C 7. Geometry of sp² hybridization is: A) Linear B) Tetrahedral C) Trigonal planar D) Octahedral Answer: C 8. sp hybridization leads to: A) Trigonal geometry B) Linear geometry C) Bent geometry D) Square planar Answer: B 9. A molecule of ethene shows: A) sp B) sp² C) sp³ D) dsp³ Answer: B 10. The hybridization of carbon in ethyne is: A) sp³ B) sp² C) sp D) sp³d Answer: C 11. Inductive effect is transmitted through: A) π bonds B) σ bonds C) Hydrogen bonds D) Lone pairs Answer: B 12. –I effect is shown by: A) –CH₃ B) –NO₂ C) –OH D) –C₂H₅ Answer: B 13. +I effect increases: A) Acidity B) Stability of carbocations C) Electronegativity D) Dipole moment Answer: B 14. Electron withdrawing group example is: A) –CH₃ B) –NH₂ C) –NO₂ D) –OH Answer: C 15. Inductive effect weakens with: A) Increase in temperature B) Decrease in distance C) Increase in distance D) Increase in concentration Answer: C 16. Resonance involves delocalization of: A) Protons B) Sigma bonds C) π-electrons D) Ions Answer: C 17. Benzene is stabilized by: A) Hydrogen bonding B) π-bond shifting C) Ionic bonding D) None of the above Answer: B 18. Which structure shows resonance? A) Ethane B) Phenol C) Cyclohexane D) Propane Answer: B 19. Resonance increases: A) Stability B) Acidity C) Polarity D) Free radicals Answer: A 20. Hyperconjugation is also called: A) No-bond resonance B) Dipole resonance C) Ionization D) Resonance Answer: A 21. Hyperconjugation stabilizes: A) Carbocations B) Free radicals only C) Lone pairs D) Alkanes only Answer: A 22. Tautomerism involves migration of: A) Proton and π-bond B) Electron only C) Atom only D) Neutron Answer: A 23. Keto-enol tautomerism is an example of: A) Structural isomerism B) Functional group isomerism C) Tautomerism D) Geometrical isomerism Answer: C 24. Dipole moment is product of: A) Charge and distance B) Force and mass C) Charge and velocity D) Mass and distance Answer: A 25. Molecules with symmetrical geometry have: A) High dipole moment B) Zero dipole moment C) Medium dipole moment D) Random dipole moment Answer: B 26. Hydrogen bonding occurs in: A) Methane B) Water C) Ethane D) Benzene Answer: B 27. Strongest hydrogen bonding is observed in: A) Water B) Methane C) Alcohols D) Ethers Answer: A 28. Electrophilic substitution occurs mainly in: A) Benzene B) Alkanes C) Alcohols D) Ethers Answer: A 29. An electrophile is: A) Electron donor B) Electron acceptor C) Neutral molecule D) Free radical Answer: B 30. Nucleophile is: A) Electron acceptor B) Electron donor C) Radical D) Cation Answer: B 31. Which of the following shows +R (resonance donating) effect? A) –NO₂ B) –OH C) –Cl D) –COOH Answer: B 32. The group showing –I and +R effect is: A) –OH B) –NO₂ C) –CN D) –CH₃ Answer: A 33. The functional group –COOH is called: A) Alcohol B) Ketone C) Carboxylic acid D) Ester Answer: C 34. The IUPAC name of CH₃CH₂OH is: A) Methanol B) Ethanol C) Propanol D) Butanol Answer: B 35. Alkylation refers to: A) Addition of alkyl group B) Removal of alkyl group C) Oxidation D) Reduction Answer: A 36. Friedel-Crafts alkylation involves: A) Addition of halogens B) Addition of alkyl groups to aromatic ring C) Substitution on alkane D) Oxidation of alcohol Answer: B 37. Geometrical isomers are also called: A) Optical isomers B) Structural isomers C) Cis-trans isomers D) Chain isomers Answer: C 38. The E/Z system is used to name: A) Optical isomers B) Geometrical isomers C) Tautomers D) Functional isomers Answer: B 39. Optical isomers differ in: A) Structure B) Configuration C) Ability to rotate plane polarized light D) Molecular weight Answer: C 40. A racemic mixture contains: A) Equal amounts of enantiomers B) Only one enantiomer C) Only one diastereomer D) No chiral molecules Answer: A 41. Alcohol functional group contains: A) –OH B) –COOH C) –NH₂ D) –SH Answer: A 42. Phenol differs from alcohol by: A) Aromatic ring attached to –OH B) Chain length C) Number of hydrogens D) Presence of carbonyl Answer: A 43. Ether functional group is: A) R–OH B) R–O–R' C) R–COOH D) R–NH₂ Answer: B 44. Alcohol can be prepared by: A) Hydration of alkenes B) Reduction of ketones C) Both A and B D) Oxidation of alkanes Answer: C 45. Oxidation of primary alcohol gives: A) Aldehyde B) Ketone C) Carboxylic acid D) Both A and C Answer: D 46. Phenol can be prepared by: A) Hydrolysis of aryl halides B) Reduction of benzene C) Both A and B D) None of above Answer: A 47. Carboxylic acid can be prepared by: A) Oxidation of primary alcohol B) Oxidation of aldehydes C) Hydrolysis of nitriles D) All of the above Answer: D 48. Carboxylic acids have: A) High boiling points B) Low solubility in water C) No acidic behavior D) Only ester groups Answer: A 49. Which of the following is a strong acid? A) Acetic acid B) Formic acid C) Sulfuric acid D) Benzoic acid Answer: C 50. The order of acidity is: A) Alcohol > Phenol > Carboxylic acid B) Carboxylic acid > Phenol > Alcohol C) Phenol > Alcohol > Carboxylic acid D) Alcohol > Carboxylic acid > Phenol Answer: B 51. Phenol is more acidic than alcohol because: A) Resonance stabilization of phenoxide ion B) Larger size of oxygen C) Higher molecular weight D) None Answer: A 52. Which group is electron withdrawing? A) –CH₃ B) –NO₂ C) –OH D) –NH₂ Answer: B 53. Electrophilic substitution reaction is characteristic of: A) Alkanes B) Aromatic rings C) Alcohols D) Ketones Answer: B 54. Friedel-Crafts acylation introduces: A) Alkyl groups B) Acyl groups C) Hydroxyl groups D) Amino groups Answer: B 55. Nomenclature rules are governed by: A) IUPAC B) FDA C) WHO D) USP Answer: A