CHEM 210 BIOCHEMISTRY MODULE 2 EXAM 2026/2027 |
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Q1: What is the hybridization state of the carbon atom in methane (CH₄) and what is the
approximate H-C-H bond angle?
A. sp² hybridization with 120° bond angles
B. sp hybridization with 180° bond angles
C. sp³ hybridization with 109.5° bond angles [CORRECT]
D. unhybridized with 90° bond angles
Correct Answer: C
Rationale: Methane's carbon undergoes sp³ hybridization, mixing one 2s and three 2p
orbitals to form four equivalent sp³ hybrid orbitals oriented tetrahedrally with 109.5°
bond angles (VSEPR theory). Each sp³ orbital overlaps with hydrogen 1s orbitals to form
sigma (σ) bonds. Option A describes trigonal planar geometry (alkenes, carbonyls).
Option B describes linear geometry (alkynes). Option D describes incorrect, non-existent
geometry. The tetrahedral geometry of sp³ carbons is fundamental to understanding the
three-dimensional structure of biomolecules including sugars and amino acids.
Q2: Which of the following molecules contains a carbon with sp² hybridization?
A. Ethane (CH₃-CH₃)
B. Ethene (ethylene, CH₂=CH₂) [CORRECT]
C. Ethyne (acetylene, HC≡CH)
D. Methane (CH₄)
Correct Answer: B
,Rationale: Ethene contains sp² hybridized carbons. Each carbon forms three sp² hybrid
orbitals (120° trigonal planar geometry) for two C-H sigma bonds and one C-C sigma
bond, with one unhybridized 2p orbital forming the π bond of the double bond. Option A
(ethane) has sp³ carbons. Option C (ethyne) has sp carbons with linear geometry.
Option D (methane) has sp³ carbon. sp² hybridization creates planar structures with
restricted rotation, enabling geometric isomerism in biological molecules like retinal
(vision) and fatty acids.
Q3: Which functional group is characterized by a carbonyl group (C=O) bonded to at
least one hydrogen atom?
A. Ketone
B. Aldehyde [CORRECT]
C. Ester
D. Amide
Correct Answer: B
Rationale: An aldehyde has the carbonyl carbon bonded to one hydrogen and one
carbon (or two hydrogens in formaldehyde), with the general formula R-CHO. The
terminal position makes aldehydes more reactive than ketones toward nucleophilic
attack and oxidation. Option A (ketone) has the carbonyl carbon bonded to two carbons
(R-CO-R'). Option C (ester) has carbonyl bonded to OR' group. Option D (amide) has
carbonyl bonded to NR'₂. In biochemistry, aldehydes appear in sugars (glucose open
form), retinal (vision), and pyridoxal phosphate (coenzyme).
Q4: What is the IUPAC name for CH₃-CH₂-CH₂-CH₃?
A. Methane
B. Ethane
C. Propane
, D. Butane [CORRECT]
Correct Answer: D
Rationale: The compound contains four carbon atoms in a straight chain with single
bonds (alkane). Prefix: but- (4 carbons), suffix: -ane (alkane) = butane. Option A is 1
carbon. Option B is 2 carbons (ethane). Option C is 3 carbons (propane). Systematic
nomenclature is essential for clear communication in biochemistry, where even small
structural differences (glucose vs. galactose) dramatically affect biological function.
The root names (meth-, eth-, prop-, but-, pent-, hex-, hept-, oct-) form the foundation for
naming biomolecules.
Q5: Which type of isomerism is demonstrated by cis-2-butene and trans-2-butene?
A. Structural (constitutional) isomerism
B. Stereoisomerism specifically geometric (cis-trans) isomerism [CORRECT]
C. Optical isomerism (enantiomerism)
D. Conformational isomerism
Correct Answer: B
Rationale: Cis-2-butene and trans-2-butene are stereoisomers (same connectivity,
different spatial arrangement) specifically geometric isomers. In cis-2-butene, the two
methyl groups are on the same side of the double bond; in trans-2-butene, they are
opposite. The restricted rotation of the C=C double bond locks these configurations.
Option A requires different connectivity. Option C requires chiral centers and
nonsuperimposable mirror images. Option D involves rotation around single bonds
(conformers interconvert rapidly). Geometric isomerism is biologically significant: trans
fats (unhealthy) vs. cis fats, and retinal isomerization in vision.
Q6: Which of the following molecules is chiral and exists as enantiomers?
Organic Chemistry Foundations | Latest Q&A Verified |
Geneva College | Pass Guaranteed - A+ Graded
Q1: What is the hybridization state of the carbon atom in methane (CH₄) and what is the
approximate H-C-H bond angle?
A. sp² hybridization with 120° bond angles
B. sp hybridization with 180° bond angles
C. sp³ hybridization with 109.5° bond angles [CORRECT]
D. unhybridized with 90° bond angles
Correct Answer: C
Rationale: Methane's carbon undergoes sp³ hybridization, mixing one 2s and three 2p
orbitals to form four equivalent sp³ hybrid orbitals oriented tetrahedrally with 109.5°
bond angles (VSEPR theory). Each sp³ orbital overlaps with hydrogen 1s orbitals to form
sigma (σ) bonds. Option A describes trigonal planar geometry (alkenes, carbonyls).
Option B describes linear geometry (alkynes). Option D describes incorrect, non-existent
geometry. The tetrahedral geometry of sp³ carbons is fundamental to understanding the
three-dimensional structure of biomolecules including sugars and amino acids.
Q2: Which of the following molecules contains a carbon with sp² hybridization?
A. Ethane (CH₃-CH₃)
B. Ethene (ethylene, CH₂=CH₂) [CORRECT]
C. Ethyne (acetylene, HC≡CH)
D. Methane (CH₄)
Correct Answer: B
,Rationale: Ethene contains sp² hybridized carbons. Each carbon forms three sp² hybrid
orbitals (120° trigonal planar geometry) for two C-H sigma bonds and one C-C sigma
bond, with one unhybridized 2p orbital forming the π bond of the double bond. Option A
(ethane) has sp³ carbons. Option C (ethyne) has sp carbons with linear geometry.
Option D (methane) has sp³ carbon. sp² hybridization creates planar structures with
restricted rotation, enabling geometric isomerism in biological molecules like retinal
(vision) and fatty acids.
Q3: Which functional group is characterized by a carbonyl group (C=O) bonded to at
least one hydrogen atom?
A. Ketone
B. Aldehyde [CORRECT]
C. Ester
D. Amide
Correct Answer: B
Rationale: An aldehyde has the carbonyl carbon bonded to one hydrogen and one
carbon (or two hydrogens in formaldehyde), with the general formula R-CHO. The
terminal position makes aldehydes more reactive than ketones toward nucleophilic
attack and oxidation. Option A (ketone) has the carbonyl carbon bonded to two carbons
(R-CO-R'). Option C (ester) has carbonyl bonded to OR' group. Option D (amide) has
carbonyl bonded to NR'₂. In biochemistry, aldehydes appear in sugars (glucose open
form), retinal (vision), and pyridoxal phosphate (coenzyme).
Q4: What is the IUPAC name for CH₃-CH₂-CH₂-CH₃?
A. Methane
B. Ethane
C. Propane
, D. Butane [CORRECT]
Correct Answer: D
Rationale: The compound contains four carbon atoms in a straight chain with single
bonds (alkane). Prefix: but- (4 carbons), suffix: -ane (alkane) = butane. Option A is 1
carbon. Option B is 2 carbons (ethane). Option C is 3 carbons (propane). Systematic
nomenclature is essential for clear communication in biochemistry, where even small
structural differences (glucose vs. galactose) dramatically affect biological function.
The root names (meth-, eth-, prop-, but-, pent-, hex-, hept-, oct-) form the foundation for
naming biomolecules.
Q5: Which type of isomerism is demonstrated by cis-2-butene and trans-2-butene?
A. Structural (constitutional) isomerism
B. Stereoisomerism specifically geometric (cis-trans) isomerism [CORRECT]
C. Optical isomerism (enantiomerism)
D. Conformational isomerism
Correct Answer: B
Rationale: Cis-2-butene and trans-2-butene are stereoisomers (same connectivity,
different spatial arrangement) specifically geometric isomers. In cis-2-butene, the two
methyl groups are on the same side of the double bond; in trans-2-butene, they are
opposite. The restricted rotation of the C=C double bond locks these configurations.
Option A requires different connectivity. Option C requires chiral centers and
nonsuperimposable mirror images. Option D involves rotation around single bonds
(conformers interconvert rapidly). Geometric isomerism is biologically significant: trans
fats (unhealthy) vs. cis fats, and retinal isomerization in vision.
Q6: Which of the following molecules is chiral and exists as enantiomers?
