CHEM 210 Biochemistry Comprehensive
Examination Modules 1-8 & Final Exam 2025/2026
Academic Year WITH CORRECT ANSWERS WELL
ELABORATED AND IN-DEPTH RATIONALE.
MODULE 1 EXAM: Foundations of Biochemistry
Section A: Atoms, Bonds, and Molecules (20 Questions)
1. Which of the following best describes the octet rule?
A) Atoms gain or lose electrons to achieve a full valence shell of 2 electrons
B) Atoms gain or lose electrons to achieve a full valence shell of 8 electrons
C) Atoms share electrons to achieve a full valence shell of 6 electrons
D) Atoms gain protons to achieve stability
ANSWER: B
Rationale: The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable
electron configuration with 8 valence electrons, similar to noble gases.
2. What type of bond forms between two atoms with electronegativity differences greater than 1.7?
A) Nonpolar covalent
B) Polar covalent
C) Ionic
D) Hydrogen bond
ANSWER: C
Rationale: When electronegativity difference exceeds 1.7, electron transfer occurs, forming ionic bonds.
Lower differences result in polar covalent (0.4-1.7) or nonpolar covalent (<0.4) bonds.
3. Which functional group is characterized by a carbonyl group attached to a hydroxyl group?
,A) Aldehyde
B) Ketone
C) Carboxylic acid
D) Ester
ANSWER: C
Rationale: Carboxylic acids contain the -COOH functional group, consisting of a carbonyl (C=O) bonded
to a hydroxyl (-OH) group.
4. The bond angle in a tetrahedral carbon atom is approximately:
A) 90°
B) 109.5°
C) 120°
D) 180°
ANSWER: B
Rationale: Tetrahedral geometry results in bond angles of 109.5° due to sp³ hybridization of the carbon
atom.
5. Which of the following is NOT a characteristic of water molecules?
A) Hydrogen bonding
B) High specific heat
C) Low surface tension
D) High dielectric constant
ANSWER: C
Rationale: Water has HIGH surface tension due to extensive hydrogen bonding between water
molecules.
6. What is the pH of a solution with [H⁺] = 1 × 10⁻⁵ M?
,A) 3
B) 5
C) 7
D) 9
ANSWER: B
Rationale: pH = -log[H⁺] = -log(1 × 10⁻⁵) = 5
7. Which type of isomer has the same molecular formula but different connectivity of atoms?
A) Geometric isomer
B) Stereoisomer
C) Structural isomer
D) Enantiomer
ANSWER: C
Rationale: Structural (constitutional) isomers differ in the connectivity of their atoms, while
stereoisomers differ in spatial arrangement.
8. A molecule with a chiral center that rotates plane-polarized light is called:
A) Racemic mixture
B) Optically active
C) Meso compound
D) Achiral
ANSWER: B
Rationale: Optically active compounds rotate plane-polarized light due to their chiral nature. Racemic
mixtures contain equal amounts of enantiomers and show no net rotation.
9. Which of the following intermolecular forces is the STRONGEST?
, A) London dispersion forces
B) Dipole-dipole interactions
C) Hydrogen bonding
D) Ionic interactions
ANSWER: D
Rationale: Ionic interactions are the strongest non-covalent interactions, followed by hydrogen bonds,
dipole-dipole, and London dispersion forces.
10. What is the primary determinant of the boiling point of a compound?
A) Molecular weight only
B) Strength of intermolecular forces
C) Polarity only
D) Number of carbons only
ANSWER: B
Rationale: Boiling points are primarily determined by the strength of intermolecular forces; stronger
forces require more energy to overcome.
11. Which pH value represents the most acidic solution?
A) 2
B) 5
C) 7
D) 9
ANSWER: A
Rationale: Lower pH values indicate higher acidity. pH 2 is highly acidic, while pH 7 is neutral and pH 9 is
basic.
12. A compound with the formula C₆H₁₂O₆ is most likely a:
Examination Modules 1-8 & Final Exam 2025/2026
Academic Year WITH CORRECT ANSWERS WELL
ELABORATED AND IN-DEPTH RATIONALE.
MODULE 1 EXAM: Foundations of Biochemistry
Section A: Atoms, Bonds, and Molecules (20 Questions)
1. Which of the following best describes the octet rule?
A) Atoms gain or lose electrons to achieve a full valence shell of 2 electrons
B) Atoms gain or lose electrons to achieve a full valence shell of 8 electrons
C) Atoms share electrons to achieve a full valence shell of 6 electrons
D) Atoms gain protons to achieve stability
ANSWER: B
Rationale: The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable
electron configuration with 8 valence electrons, similar to noble gases.
2. What type of bond forms between two atoms with electronegativity differences greater than 1.7?
A) Nonpolar covalent
B) Polar covalent
C) Ionic
D) Hydrogen bond
ANSWER: C
Rationale: When electronegativity difference exceeds 1.7, electron transfer occurs, forming ionic bonds.
Lower differences result in polar covalent (0.4-1.7) or nonpolar covalent (<0.4) bonds.
3. Which functional group is characterized by a carbonyl group attached to a hydroxyl group?
,A) Aldehyde
B) Ketone
C) Carboxylic acid
D) Ester
ANSWER: C
Rationale: Carboxylic acids contain the -COOH functional group, consisting of a carbonyl (C=O) bonded
to a hydroxyl (-OH) group.
4. The bond angle in a tetrahedral carbon atom is approximately:
A) 90°
B) 109.5°
C) 120°
D) 180°
ANSWER: B
Rationale: Tetrahedral geometry results in bond angles of 109.5° due to sp³ hybridization of the carbon
atom.
5. Which of the following is NOT a characteristic of water molecules?
A) Hydrogen bonding
B) High specific heat
C) Low surface tension
D) High dielectric constant
ANSWER: C
Rationale: Water has HIGH surface tension due to extensive hydrogen bonding between water
molecules.
6. What is the pH of a solution with [H⁺] = 1 × 10⁻⁵ M?
,A) 3
B) 5
C) 7
D) 9
ANSWER: B
Rationale: pH = -log[H⁺] = -log(1 × 10⁻⁵) = 5
7. Which type of isomer has the same molecular formula but different connectivity of atoms?
A) Geometric isomer
B) Stereoisomer
C) Structural isomer
D) Enantiomer
ANSWER: C
Rationale: Structural (constitutional) isomers differ in the connectivity of their atoms, while
stereoisomers differ in spatial arrangement.
8. A molecule with a chiral center that rotates plane-polarized light is called:
A) Racemic mixture
B) Optically active
C) Meso compound
D) Achiral
ANSWER: B
Rationale: Optically active compounds rotate plane-polarized light due to their chiral nature. Racemic
mixtures contain equal amounts of enantiomers and show no net rotation.
9. Which of the following intermolecular forces is the STRONGEST?
, A) London dispersion forces
B) Dipole-dipole interactions
C) Hydrogen bonding
D) Ionic interactions
ANSWER: D
Rationale: Ionic interactions are the strongest non-covalent interactions, followed by hydrogen bonds,
dipole-dipole, and London dispersion forces.
10. What is the primary determinant of the boiling point of a compound?
A) Molecular weight only
B) Strength of intermolecular forces
C) Polarity only
D) Number of carbons only
ANSWER: B
Rationale: Boiling points are primarily determined by the strength of intermolecular forces; stronger
forces require more energy to overcome.
11. Which pH value represents the most acidic solution?
A) 2
B) 5
C) 7
D) 9
ANSWER: A
Rationale: Lower pH values indicate higher acidity. pH 2 is highly acidic, while pH 7 is neutral and pH 9 is
basic.
12. A compound with the formula C₆H₁₂O₆ is most likely a:
