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Organic Chemistry - Janice Gorzynski Smith |
Foundations, Structure & Stereochemistry
Practice Exam
150 original questions with answers and detailed explanations
QUESTIONS FORMAT COVERAGE
150 A-D + Explanations Foundations
Original practice questions for independent study and exam preparation.
,Foundations, Structure & Stereochemistry Practice Exam
Practice Questions
Choose the best answer for each item. The answer and a detailed explanation follow each question.
Hybridization and bonding
1. Which statement best describes the carbonyl carbon in acetone?
A. tetrahedral with four sigma bonds
B. sp hybridized
C. sp3 hybridized
D. sp2 hybridized and trigonal planar
Answer: D
Explanation: A carbonyl carbon has three electron domains and a trigonal-planar arrangement, so it is sp2 hybridized. One
unhybridized p orbital participates in the C=O pi bond. An sp3 description would not allow the required pi bonding.
Hybridization and bonding
2. Which statement best describes the carbon atom of a nitrile group, C#N?
A. sp2 hybridized
B. sp hybridized and linear
C. sp3 hybridized
D. tetrahedral
Answer: B
Explanation: A nitrile carbon has two electron domains and therefore uses sp hybrid orbitals. Two unhybridized p orbitals form the two
pi bonds of the triple bond. The resulting geometry at that carbon is linear.
Hybridization and bonding
3. Which statement best describes a saturated carbon in ethane?
A. sp2 hybridized
B. trigonal planar
C. sp3 hybridized with tetrahedral geometry
D. sp hybridized
Answer: C
Explanation: Each carbon in ethane forms four sigma bonds and has four electron domains. That arrangement corresponds to sp3
hybridization and approximately tetrahedral geometry. No unhybridized p orbital is needed because there is no pi bond.
Hybridization and bonding
4. Which statement best describes a carbon atom in benzene?
A. tetrahedral and nonconjugated
B. sp3 hybridized
C. sp2 hybridized and part of a conjugated pi system
D. sp hybridized
Answer: C
Explanation: Each benzene carbon is trigonal planar and contributes one p orbital to the aromatic pi system. Therefore every ring
carbon is sp2 hybridized. sp3 hybridization would interrupt continuous p-orbital overlap.
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,Foundations, Structure & Stereochemistry Practice Exam
Hybridization and bonding
5. Which statement best describes the positively charged carbon of a simple carbocation?
A. sp3 hybridized with a lone pair
B. sp2 hybridized with an empty p orbital
C. sp hybridized with two lone pairs
D. tetrahedral with a filled p orbital
Answer: B
Explanation: A classical carbocation is approximately trigonal planar at the positively charged carbon. It has an empty p orbital that can
overlap with neighboring pi bonds or lone pairs. This geometry is described by sp2 hybridization.
Hybridization and bonding
6. Which statement best describes the negatively charged carbon of a simple alkyl carbanion?
A. a carbonyl carbon
B. usually pyramidal and approximately sp3 hybridized
C. necessarily trigonal planar and sp2
D. necessarily linear and sp
Answer: B
Explanation: A simple localized alkyl carbanion typically has three sigma bonds and a lone pair, giving roughly tetrahedral electron
geometry. Its carbon is therefore commonly described as approximately sp3 hybridized and pyramidal. Resonance-stabilized
carbanions may become more planar, but the simple alkyl case is not sp or carbonyl-like.
Hybridization and bonding
7. Which statement best describes a carbon atom of an isolated alkene?
A. sp3 hybridized
B. sp hybridized
C. sp2 hybridized with one unhybridized p orbital
D. sp3d hybridized
Answer: C
Explanation: Each alkene carbon makes three sigma bonds or electron-domain interactions and retains one p orbital. The p orbitals
overlap to form the pi bond of C=C. This is the characteristic bonding picture for sp2 carbon.
Hybridization and bonding
8. Which statement best describes a carbon atom of an alkyne?
A. sp hybridized with two unhybridized p orbitals
B. tetrahedral
C. sp2 hybridized
D. sp3 hybridized
Answer: A
Explanation: An alkyne carbon has two electron domains and is linear. Two unhybridized p orbitals on each carbon form the two pi
bonds. The remaining sp orbitals form sigma bonds along the internuclear axis.
Hybridization and bonding
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, Foundations, Structure & Stereochemistry Practice Exam
9. Which statement best describes the oxygen atom of a simple alcohol?
A. linear with no lone pairs
B. approximately sp3 hybridized with two lone pairs
C. sp2 carbonyl-like oxygen only
D. sp hybridized
Answer: B
Explanation: An alcohol oxygen has two sigma bonds and two lone pairs, giving four electron domains. That is consistent with
approximately sp3 hybridization and a bent molecular geometry. The lone pairs strongly influence both shape and reactivity.
Hybridization and bonding
10. Which statement best describes the nitrogen atom of a typical trialkylamine?
A. positively charged by definition
B. sp and linear
C. sp2 and strictly planar
D. approximately sp3 hybridized and pyramidal
Answer: D
Explanation: A neutral trialkylamine nitrogen has three sigma bonds and one lone pair. Its electron geometry is roughly tetrahedral and
its molecular shape is pyramidal. The lone pair makes the amine basic and nucleophilic.
Resonance and structure
11. Which statement best describes the nitrogen atom of an amide?
A. approximately sp2 hybridized because the lone pair is conjugated with the carbonyl
B. sp3 and freely rotating
C. unable to participate in resonance
D. sp and linear
Answer: A
Explanation: The amide nitrogen lone pair overlaps with the adjacent carbonyl pi system. This conjugation gives the C-N bond partial
double-bond character and favors a planar, sp2-like nitrogen. Restricted rotation is a direct consequence of this resonance stabilization.
Hybridization and bonding
12. Which statement best describes the carbon atom directly bearing a hydroxyl group in methanol?
A. sp2 hybridized
B. sp hybridized
C. sp3 hybridized
D. a carbonyl carbon
Answer: C
Explanation: The carbon of methanol forms four sigma bonds: three C-H bonds and one C-O bond. Four electron domains correspond
to sp3 hybridization. There is no pi bond at that carbon.
Acid-base chemistry
13. Which statement best describes acetic acid compared with ethanol, phenol, and ethane?
A. ethanol is strongest
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Organic Chemistry - Janice Gorzynski Smith |
Foundations, Structure & Stereochemistry
Practice Exam
150 original questions with answers and detailed explanations
QUESTIONS FORMAT COVERAGE
150 A-D + Explanations Foundations
Original practice questions for independent study and exam preparation.
,Foundations, Structure & Stereochemistry Practice Exam
Practice Questions
Choose the best answer for each item. The answer and a detailed explanation follow each question.
Hybridization and bonding
1. Which statement best describes the carbonyl carbon in acetone?
A. tetrahedral with four sigma bonds
B. sp hybridized
C. sp3 hybridized
D. sp2 hybridized and trigonal planar
Answer: D
Explanation: A carbonyl carbon has three electron domains and a trigonal-planar arrangement, so it is sp2 hybridized. One
unhybridized p orbital participates in the C=O pi bond. An sp3 description would not allow the required pi bonding.
Hybridization and bonding
2. Which statement best describes the carbon atom of a nitrile group, C#N?
A. sp2 hybridized
B. sp hybridized and linear
C. sp3 hybridized
D. tetrahedral
Answer: B
Explanation: A nitrile carbon has two electron domains and therefore uses sp hybrid orbitals. Two unhybridized p orbitals form the two
pi bonds of the triple bond. The resulting geometry at that carbon is linear.
Hybridization and bonding
3. Which statement best describes a saturated carbon in ethane?
A. sp2 hybridized
B. trigonal planar
C. sp3 hybridized with tetrahedral geometry
D. sp hybridized
Answer: C
Explanation: Each carbon in ethane forms four sigma bonds and has four electron domains. That arrangement corresponds to sp3
hybridization and approximately tetrahedral geometry. No unhybridized p orbital is needed because there is no pi bond.
Hybridization and bonding
4. Which statement best describes a carbon atom in benzene?
A. tetrahedral and nonconjugated
B. sp3 hybridized
C. sp2 hybridized and part of a conjugated pi system
D. sp hybridized
Answer: C
Explanation: Each benzene carbon is trigonal planar and contributes one p orbital to the aromatic pi system. Therefore every ring
carbon is sp2 hybridized. sp3 hybridization would interrupt continuous p-orbital overlap.
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,Foundations, Structure & Stereochemistry Practice Exam
Hybridization and bonding
5. Which statement best describes the positively charged carbon of a simple carbocation?
A. sp3 hybridized with a lone pair
B. sp2 hybridized with an empty p orbital
C. sp hybridized with two lone pairs
D. tetrahedral with a filled p orbital
Answer: B
Explanation: A classical carbocation is approximately trigonal planar at the positively charged carbon. It has an empty p orbital that can
overlap with neighboring pi bonds or lone pairs. This geometry is described by sp2 hybridization.
Hybridization and bonding
6. Which statement best describes the negatively charged carbon of a simple alkyl carbanion?
A. a carbonyl carbon
B. usually pyramidal and approximately sp3 hybridized
C. necessarily trigonal planar and sp2
D. necessarily linear and sp
Answer: B
Explanation: A simple localized alkyl carbanion typically has three sigma bonds and a lone pair, giving roughly tetrahedral electron
geometry. Its carbon is therefore commonly described as approximately sp3 hybridized and pyramidal. Resonance-stabilized
carbanions may become more planar, but the simple alkyl case is not sp or carbonyl-like.
Hybridization and bonding
7. Which statement best describes a carbon atom of an isolated alkene?
A. sp3 hybridized
B. sp hybridized
C. sp2 hybridized with one unhybridized p orbital
D. sp3d hybridized
Answer: C
Explanation: Each alkene carbon makes three sigma bonds or electron-domain interactions and retains one p orbital. The p orbitals
overlap to form the pi bond of C=C. This is the characteristic bonding picture for sp2 carbon.
Hybridization and bonding
8. Which statement best describes a carbon atom of an alkyne?
A. sp hybridized with two unhybridized p orbitals
B. tetrahedral
C. sp2 hybridized
D. sp3 hybridized
Answer: A
Explanation: An alkyne carbon has two electron domains and is linear. Two unhybridized p orbitals on each carbon form the two pi
bonds. The remaining sp orbitals form sigma bonds along the internuclear axis.
Hybridization and bonding
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, Foundations, Structure & Stereochemistry Practice Exam
9. Which statement best describes the oxygen atom of a simple alcohol?
A. linear with no lone pairs
B. approximately sp3 hybridized with two lone pairs
C. sp2 carbonyl-like oxygen only
D. sp hybridized
Answer: B
Explanation: An alcohol oxygen has two sigma bonds and two lone pairs, giving four electron domains. That is consistent with
approximately sp3 hybridization and a bent molecular geometry. The lone pairs strongly influence both shape and reactivity.
Hybridization and bonding
10. Which statement best describes the nitrogen atom of a typical trialkylamine?
A. positively charged by definition
B. sp and linear
C. sp2 and strictly planar
D. approximately sp3 hybridized and pyramidal
Answer: D
Explanation: A neutral trialkylamine nitrogen has three sigma bonds and one lone pair. Its electron geometry is roughly tetrahedral and
its molecular shape is pyramidal. The lone pair makes the amine basic and nucleophilic.
Resonance and structure
11. Which statement best describes the nitrogen atom of an amide?
A. approximately sp2 hybridized because the lone pair is conjugated with the carbonyl
B. sp3 and freely rotating
C. unable to participate in resonance
D. sp and linear
Answer: A
Explanation: The amide nitrogen lone pair overlaps with the adjacent carbonyl pi system. This conjugation gives the C-N bond partial
double-bond character and favors a planar, sp2-like nitrogen. Restricted rotation is a direct consequence of this resonance stabilization.
Hybridization and bonding
12. Which statement best describes the carbon atom directly bearing a hydroxyl group in methanol?
A. sp2 hybridized
B. sp hybridized
C. sp3 hybridized
D. a carbonyl carbon
Answer: C
Explanation: The carbon of methanol forms four sigma bonds: three C-H bonds and one C-O bond. Four electron domains correspond
to sp3 hybridization. There is no pi bond at that carbon.
Acid-base chemistry
13. Which statement best describes acetic acid compared with ethanol, phenol, and ethane?
A. ethanol is strongest
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