CHEM 219 ORGANIC CHEMISTRY
PRACTICE EXAM (2026/2027)
QUESTIONS WITH CORRECT ANSWERS
2026/2027 UPDATE. JUST RELEASED
1. Which of the following molecules contains a chiral center?
A. 2-chloropropane
B. 1-chlorobutane
C. 2-chlorobutane
D. 2-methylpropane
Answer: C
Conceptual Explanation: 2-chlorobutane has a carbon (C2) attached to four different
groups: H, Cl, methyl, and ethyl, making it a chiral center.
2. Which statement best describes the SN2 reaction mechanism?
A. It involves a two-step process with a carbocation intermediate.
B. The rate depends only on the concentration of the substrate.
C. It is favored by bulky substituents on the substrate carbon.
D. It occurs with complete inversion of configuration at the chiral center.
,Answer: D
Conceptual Explanation: SN2 is a concerted, one-step bimolecular reaction where the
nucleophile attacks from the backside, leading to Walden inversion.
3. Identify the strongest acid among the following compounds.
A. Ethanol
B. Phenol
C. Acetic acid
D. Trichloroacetic acid
Answer: D
Conceptual Explanation: The inductive effect of the three chlorine atoms stabilizes the
conjugate base, making trichloroacetic acid much more acidic than the others.
4. Which reagent is used for the anti-Markovnikov hydration of an alkene?
A. Hg(OAc)2, H2O followed by NaBH4
B. BH3-THF followed by H2O2, NaOH
C. Dilute H2SO4
D. OsO4 followed by NaHSO3
Answer: B
, Conceptual Explanation: Hydroboration-oxidation yields anti-Markovnikov addition of
water with syn-stereochemistry.
5. Which of the following describes the relationship between (2R, 3R)-tartaric acid and (2S,
3S)-tartaric acid?
A. Meso compounds
B. Diastereomers
C. Enantiomers
D. Constitutional isomers
Answer: C
Conceptual Explanation: Molecules that are non-superimposable mirror images (all chiral
centers inverted) are enantiomers.
6. Which functional group is characterized by a strong, broad IR absorption band between
3200-3600 cm-1?
A. Carbonyl (C=O)
B. Alcohol (O-H)
C. Alkyne (C≡C)
D. Nitrile (C≡N)
Answer: B
PRACTICE EXAM (2026/2027)
QUESTIONS WITH CORRECT ANSWERS
2026/2027 UPDATE. JUST RELEASED
1. Which of the following molecules contains a chiral center?
A. 2-chloropropane
B. 1-chlorobutane
C. 2-chlorobutane
D. 2-methylpropane
Answer: C
Conceptual Explanation: 2-chlorobutane has a carbon (C2) attached to four different
groups: H, Cl, methyl, and ethyl, making it a chiral center.
2. Which statement best describes the SN2 reaction mechanism?
A. It involves a two-step process with a carbocation intermediate.
B. The rate depends only on the concentration of the substrate.
C. It is favored by bulky substituents on the substrate carbon.
D. It occurs with complete inversion of configuration at the chiral center.
,Answer: D
Conceptual Explanation: SN2 is a concerted, one-step bimolecular reaction where the
nucleophile attacks from the backside, leading to Walden inversion.
3. Identify the strongest acid among the following compounds.
A. Ethanol
B. Phenol
C. Acetic acid
D. Trichloroacetic acid
Answer: D
Conceptual Explanation: The inductive effect of the three chlorine atoms stabilizes the
conjugate base, making trichloroacetic acid much more acidic than the others.
4. Which reagent is used for the anti-Markovnikov hydration of an alkene?
A. Hg(OAc)2, H2O followed by NaBH4
B. BH3-THF followed by H2O2, NaOH
C. Dilute H2SO4
D. OsO4 followed by NaHSO3
Answer: B
, Conceptual Explanation: Hydroboration-oxidation yields anti-Markovnikov addition of
water with syn-stereochemistry.
5. Which of the following describes the relationship between (2R, 3R)-tartaric acid and (2S,
3S)-tartaric acid?
A. Meso compounds
B. Diastereomers
C. Enantiomers
D. Constitutional isomers
Answer: C
Conceptual Explanation: Molecules that are non-superimposable mirror images (all chiral
centers inverted) are enantiomers.
6. Which functional group is characterized by a strong, broad IR absorption band between
3200-3600 cm-1?
A. Carbonyl (C=O)
B. Alcohol (O-H)
C. Alkyne (C≡C)
D. Nitrile (C≡N)
Answer: B
