Organic Chemistry 1 ACS
Questions Final Exam
Section 1: Structure and Bonding
1. Which of the following molecules has the highest dipole moment?
A. CO₂
B. CH₄
C. NH₃
D. CCl₄
✅ Answer: C. NH₃
Explanation: NH₃ is polar due to its trigonal pyramidal shape; CO₂ and CCl₄ are
nonpolar.
2. Which hybridization corresponds to the carbon in ethyne (C₂H₂)?
A. sp³
B. sp²
C. sp
D. none of these
✅ Answer: C. sp
Explanation: Each carbon in ethyne forms a triple bond (one σ and two π bonds),
requiring sp hybridization.
3. The strongest acid among the following is:
A. CH₄
,B. NH₃
C. H₂O
D. HF
✅ Answer: D. HF
Explanation: Acidity increases with electronegativity and bond polarity; HF is the
most acidic.
Section 2: Nomenclature
4. What is the correct IUPAC name for (CH₃)₂CHCH₂CH₃?
A. Pentane
B. 2-Methylbutane
C. 3-Methylbutane
D. Isopentane
✅ Answer: B. 2-Methylbutane
Explanation: The parent chain is butane, with a methyl substituent at carbon 2.
5. The correct name for CH₃CH₂CH₂OH is:
A. Ethanol
B. Propan-1-ol
C. Isopropanol
D. Propan-2-ol
✅ Answer: B. Propan-1-ol
Explanation: The OH group is on the first carbon.
Section 3: Stereochemistry
6. Which of the following pairs are enantiomers?
A. (R)-2-butanol and (S)-2-butanol
,B. cis-2-butene and trans-2-butene
C. meso-2,3-butanediol and racemic mixture
D. n-butane and isobutane
✅ Answer: A. (R)-2-butanol and (S)-2-butanol
Explanation: They are nonsuperimposable mirror images.
7. A molecule with two stereocenters can have a maximum of how many
stereoisomers?
A. 2
B. 3
C. 4
D. 8
✅ Answer: C. 4
Explanation: Maximum possible = 2ⁿ = 2² = 4, unless a meso form reduces the
number.
Section 4: Reaction Mechanisms
8. Which reaction proceeds via an SN1 mechanism?
A. CH₃Br + NaOH → CH₃OH
B. (CH₃)₃CBr + H₂O → (CH₃)₃COH
C. CH₃CH₂Br + NaCN → CH₃CH₂CN
D. CH₃CH₂I + NaOH → CH₃CH₂OH
✅ Answer: B. (CH₃)₃CBr + H₂O → (CH₃)₃COH
Explanation: Tertiary alkyl halides undergo SN1 due to stable carbocation formation.
9. What is the rate law for an SN2 reaction?
A. rate = k[substrate]
B. rate = k[nucleophile]
, C. rate = k[substrate][nucleophile]
D. rate = k
✅ Answer: C. rate = k[substrate][nucleophile]
Explanation: SN2 reactions are bimolecular, depending on both substrate and
nucleophile concentration.
10. Which of the following is an electrophile?
A. NH₃
B. H₂O
C. CH₃⁺
D. Cl⁻
✅ Answer: C. CH₃⁺
Explanation: Electrophiles are electron-deficient species seeking electrons.
Section 5: Alkenes and Alkynes
11. Which reagent adds water to an alkene following Markovnikov’s rule?
A. H₂O / H₂SO₄
B. BH₃ / H₂O₂
C. Hg(OAc)₂ / H₂O then NaBH₄
D. O₃ / Zn
✅ Answer: A. H₂O / H₂SO₄
Explanation: Acid-catalyzed hydration adds –OH to the more substituted carbon.
12. The product of hydrogenation of 2-butene is:
A. Butane
B. Butyne
C. Ethane
D. Cyclobutane
Questions Final Exam
Section 1: Structure and Bonding
1. Which of the following molecules has the highest dipole moment?
A. CO₂
B. CH₄
C. NH₃
D. CCl₄
✅ Answer: C. NH₃
Explanation: NH₃ is polar due to its trigonal pyramidal shape; CO₂ and CCl₄ are
nonpolar.
2. Which hybridization corresponds to the carbon in ethyne (C₂H₂)?
A. sp³
B. sp²
C. sp
D. none of these
✅ Answer: C. sp
Explanation: Each carbon in ethyne forms a triple bond (one σ and two π bonds),
requiring sp hybridization.
3. The strongest acid among the following is:
A. CH₄
,B. NH₃
C. H₂O
D. HF
✅ Answer: D. HF
Explanation: Acidity increases with electronegativity and bond polarity; HF is the
most acidic.
Section 2: Nomenclature
4. What is the correct IUPAC name for (CH₃)₂CHCH₂CH₃?
A. Pentane
B. 2-Methylbutane
C. 3-Methylbutane
D. Isopentane
✅ Answer: B. 2-Methylbutane
Explanation: The parent chain is butane, with a methyl substituent at carbon 2.
5. The correct name for CH₃CH₂CH₂OH is:
A. Ethanol
B. Propan-1-ol
C. Isopropanol
D. Propan-2-ol
✅ Answer: B. Propan-1-ol
Explanation: The OH group is on the first carbon.
Section 3: Stereochemistry
6. Which of the following pairs are enantiomers?
A. (R)-2-butanol and (S)-2-butanol
,B. cis-2-butene and trans-2-butene
C. meso-2,3-butanediol and racemic mixture
D. n-butane and isobutane
✅ Answer: A. (R)-2-butanol and (S)-2-butanol
Explanation: They are nonsuperimposable mirror images.
7. A molecule with two stereocenters can have a maximum of how many
stereoisomers?
A. 2
B. 3
C. 4
D. 8
✅ Answer: C. 4
Explanation: Maximum possible = 2ⁿ = 2² = 4, unless a meso form reduces the
number.
Section 4: Reaction Mechanisms
8. Which reaction proceeds via an SN1 mechanism?
A. CH₃Br + NaOH → CH₃OH
B. (CH₃)₃CBr + H₂O → (CH₃)₃COH
C. CH₃CH₂Br + NaCN → CH₃CH₂CN
D. CH₃CH₂I + NaOH → CH₃CH₂OH
✅ Answer: B. (CH₃)₃CBr + H₂O → (CH₃)₃COH
Explanation: Tertiary alkyl halides undergo SN1 due to stable carbocation formation.
9. What is the rate law for an SN2 reaction?
A. rate = k[substrate]
B. rate = k[nucleophile]
, C. rate = k[substrate][nucleophile]
D. rate = k
✅ Answer: C. rate = k[substrate][nucleophile]
Explanation: SN2 reactions are bimolecular, depending on both substrate and
nucleophile concentration.
10. Which of the following is an electrophile?
A. NH₃
B. H₂O
C. CH₃⁺
D. Cl⁻
✅ Answer: C. CH₃⁺
Explanation: Electrophiles are electron-deficient species seeking electrons.
Section 5: Alkenes and Alkynes
11. Which reagent adds water to an alkene following Markovnikov’s rule?
A. H₂O / H₂SO₄
B. BH₃ / H₂O₂
C. Hg(OAc)₂ / H₂O then NaBH₄
D. O₃ / Zn
✅ Answer: A. H₂O / H₂SO₄
Explanation: Acid-catalyzed hydration adds –OH to the more substituted carbon.
12. The product of hydrogenation of 2-butene is:
A. Butane
B. Butyne
C. Ethane
D. Cyclobutane
