CHEM 219 FINAL EXAM PREP -
ORGANIC CHEMISTRY AND
BIOCHEMISTRY QUESTIONS WITH
CORRECT ANSWERS 2026/2027 UPDATE.
JUST RELEASED
1. Which of the following describes the hybridization of the carbon atoms in ethyne
(acetylene)?
A. sp3
B. sp2
C. dsp2
D. sp
Answer: D
Conceptual Explanation: In ethyne (C2H2), each carbon is triple-bonded to the other
carbon and single-bonded to a hydrogen, requiring linear geometry and sp hybridization.
2. Which reagent is best suited for the oxidation of a primary alcohol to an aldehyde without
further oxidation to a carboxylic acid?
A. PCC (Pyridinium chlorochromate) in CH2Cl2
B. K2Cr2O7 / H2SO4
,C. KMnO4 / NaOH
D. LiAlH4 in ether
Answer: A
Conceptual Explanation: PCC is a mild oxidizing agent that stops at the aldehyde stage for
primary alcohols, whereas Jones reagent or KMnO4 would oxidize it to a carboxylic acid.
3. In the SN2 reaction mechanism, which of the following statements is true regarding the
reaction rate?
A. The rate depends only on the concentration of the electrophile.
B. The reaction proceeds with a carbocation intermediate.
C. The rate is bimolecular, depending on both nucleophile and substrate.
D. Tertiary halides react faster than primary halides.
Answer: C
Conceptual Explanation: SN2 stands for Substitution Nucleophilic Bimolecular, meaning
the rate law is Rate = k[Substrate][Nucleophile].
4. Which of the following compounds is considered aromatic according to Hückel’s Rule?
A. Cyclobutadiene
B. Benzene
C. Cyclooctatetraene
, D. Cyclohexene
Answer: B
Conceptual Explanation: Benzene follows Hückel’s Rule (4n+2 pi electrons where n=1,
total 6), is planar, cyclic, and fully conjugated.
5. What is the relationship between (R)-2-butanol and (S)-2-butanol?
A. Enantiomers
B. Diastereomers
C. Constitutional isomers
D. Identical compounds
Answer: A
Conceptual Explanation: Enantiomers are non-superimposable mirror images; (R) and
(S) configurations at the same chiral center indicate mirror images.
6. Which amino acid is classified as ‘non-polar’ and contains a thioether group?
A. Cysteine
B. Serine
C. Methionine
D. Threonine
Answer: C
ORGANIC CHEMISTRY AND
BIOCHEMISTRY QUESTIONS WITH
CORRECT ANSWERS 2026/2027 UPDATE.
JUST RELEASED
1. Which of the following describes the hybridization of the carbon atoms in ethyne
(acetylene)?
A. sp3
B. sp2
C. dsp2
D. sp
Answer: D
Conceptual Explanation: In ethyne (C2H2), each carbon is triple-bonded to the other
carbon and single-bonded to a hydrogen, requiring linear geometry and sp hybridization.
2. Which reagent is best suited for the oxidation of a primary alcohol to an aldehyde without
further oxidation to a carboxylic acid?
A. PCC (Pyridinium chlorochromate) in CH2Cl2
B. K2Cr2O7 / H2SO4
,C. KMnO4 / NaOH
D. LiAlH4 in ether
Answer: A
Conceptual Explanation: PCC is a mild oxidizing agent that stops at the aldehyde stage for
primary alcohols, whereas Jones reagent or KMnO4 would oxidize it to a carboxylic acid.
3. In the SN2 reaction mechanism, which of the following statements is true regarding the
reaction rate?
A. The rate depends only on the concentration of the electrophile.
B. The reaction proceeds with a carbocation intermediate.
C. The rate is bimolecular, depending on both nucleophile and substrate.
D. Tertiary halides react faster than primary halides.
Answer: C
Conceptual Explanation: SN2 stands for Substitution Nucleophilic Bimolecular, meaning
the rate law is Rate = k[Substrate][Nucleophile].
4. Which of the following compounds is considered aromatic according to Hückel’s Rule?
A. Cyclobutadiene
B. Benzene
C. Cyclooctatetraene
, D. Cyclohexene
Answer: B
Conceptual Explanation: Benzene follows Hückel’s Rule (4n+2 pi electrons where n=1,
total 6), is planar, cyclic, and fully conjugated.
5. What is the relationship between (R)-2-butanol and (S)-2-butanol?
A. Enantiomers
B. Diastereomers
C. Constitutional isomers
D. Identical compounds
Answer: A
Conceptual Explanation: Enantiomers are non-superimposable mirror images; (R) and
(S) configurations at the same chiral center indicate mirror images.
6. Which amino acid is classified as ‘non-polar’ and contains a thioether group?
A. Cysteine
B. Serine
C. Methionine
D. Threonine
Answer: C
