CHEM 2323 exam questions with answers and rationales 2026 for university of
Houston spring final exam
CHEM 2323 Organic Chemistry I - Exam Questions (2026)
Part 1: Structure, Bonding, and Nomenclature (Questions 1-40)
Q1. What is the hybridization state of the carbon atoms in methane?
A) sp
B) sp²
C) sp³
D) sp³d
Answer: C
Rationale: Methane (CH₄) has four sigma bonds and a tetrahedral geometry.
Carbon uses four equivalent sp³ hybrid orbitals to form these bonds, with bond
angles of approximately 109.5°.
Q2. Which of the following correctly describes the carbon-carbon bond in
ethylene (C₂H₄)?
A) One sigma bond only
,B) One pi bond only
C) One sigma and one pi bond
D) Two pi bonds
Answer: C
Rationale: Ethylene contains a double bond: one sigma bond (formed by end-on
overlap of sp² hybrid orbitals) and one pi bond (formed by side-on overlap of
unhybridized p orbitals).
Q3. What is the IUPAC name for the compound CH₃CH₂CH₂CH₃?
A) Butane
B) Propane
C) Pentane
D) Ethane
Answer: A
Rationale: The four-carbon unbranched alkane is named butane. The prefix "but-"
indicates four carbons, and the suffix "-ane" indicates a saturated hydrocarbon.
,Q4. Which functional group is characterized by the presence of a carbonyl group
bonded to two carbon atoms?
A) Aldehyde
B) Ketone
C) Carboxylic acid
D) Ester
Answer: B
Rationale: A ketone has a carbonyl group (C=O) bonded to two carbon atoms (R-
CO-R'). Aldehydes have the carbonyl at the end of the chain (R-CHO), carboxylic
acids have -COOH, and esters have -COOR.
Q5. What is the correct IUPAC name for the compound (CH₃)₂CHCH₂CH₂CH₃?
A) 2-Methylpentane
B) 3-Methylpentane
C) 2-Methylhexane
D) Isohexane
Answer: A
, Rationale: The longest continuous carbon chain is five carbons (pentane). The
methyl substituent is on the second carbon, giving 2-methylpentane.
Q6. Which alkyl group is formed by removing one hydrogen from methane?
A) Methyl
B) Ethyl
C) Propyl
D) Butyl
Answer: A
Rationale: Removing one H from CH₄ gives the methyl group (-CH₃). The methyl
group is the simplest alkyl substituent.
Q7. What is the molecular formula for cyclopentane?
A) C₅H₁₀
B) C₅H₁₂
C) C₅H₈
D) C₅H₆
Answer: A
Houston spring final exam
CHEM 2323 Organic Chemistry I - Exam Questions (2026)
Part 1: Structure, Bonding, and Nomenclature (Questions 1-40)
Q1. What is the hybridization state of the carbon atoms in methane?
A) sp
B) sp²
C) sp³
D) sp³d
Answer: C
Rationale: Methane (CH₄) has four sigma bonds and a tetrahedral geometry.
Carbon uses four equivalent sp³ hybrid orbitals to form these bonds, with bond
angles of approximately 109.5°.
Q2. Which of the following correctly describes the carbon-carbon bond in
ethylene (C₂H₄)?
A) One sigma bond only
,B) One pi bond only
C) One sigma and one pi bond
D) Two pi bonds
Answer: C
Rationale: Ethylene contains a double bond: one sigma bond (formed by end-on
overlap of sp² hybrid orbitals) and one pi bond (formed by side-on overlap of
unhybridized p orbitals).
Q3. What is the IUPAC name for the compound CH₃CH₂CH₂CH₃?
A) Butane
B) Propane
C) Pentane
D) Ethane
Answer: A
Rationale: The four-carbon unbranched alkane is named butane. The prefix "but-"
indicates four carbons, and the suffix "-ane" indicates a saturated hydrocarbon.
,Q4. Which functional group is characterized by the presence of a carbonyl group
bonded to two carbon atoms?
A) Aldehyde
B) Ketone
C) Carboxylic acid
D) Ester
Answer: B
Rationale: A ketone has a carbonyl group (C=O) bonded to two carbon atoms (R-
CO-R'). Aldehydes have the carbonyl at the end of the chain (R-CHO), carboxylic
acids have -COOH, and esters have -COOR.
Q5. What is the correct IUPAC name for the compound (CH₃)₂CHCH₂CH₂CH₃?
A) 2-Methylpentane
B) 3-Methylpentane
C) 2-Methylhexane
D) Isohexane
Answer: A
, Rationale: The longest continuous carbon chain is five carbons (pentane). The
methyl substituent is on the second carbon, giving 2-methylpentane.
Q6. Which alkyl group is formed by removing one hydrogen from methane?
A) Methyl
B) Ethyl
C) Propyl
D) Butyl
Answer: A
Rationale: Removing one H from CH₄ gives the methyl group (-CH₃). The methyl
group is the simplest alkyl substituent.
Q7. What is the molecular formula for cyclopentane?
A) C₅H₁₀
B) C₅H₁₂
C) C₅H₈
D) C₅H₆
Answer: A
