CHEM 210 Biochemistry Module 2 Exam – Portage
Learning Latest 2026/2027 Update | Water, pH, Buffers
& Aqueous Systems | Bold Answers with
Explanations
Introduction
This practice exam is designed for students preparing for the CHEM 210 Module 2
Exam at Portage Learning. Module 2 focuses on fundamental biochemistry concepts
related to water and aqueous systems, including:
Water Chemistry – Molecular shape, polarity, hydrogen bonding
pH & Buffers – Autoionization of water, acid-base equilibrium
Intermolecular Forces – Hydrogen bonds, dipole-dipole interactions, London
dispersion forces
Thermodynamics – Enthalpy, entropy, Gibbs free energy
Acid Strength & pKa – Ka, pKa calculations, acid strength comparisons
Each question includes the correct answer in bold and a detailed rationale based on the
Portage Learning curriculum.
Section 1: Water Chemistry & Molecular Properties (Questions 1-20)
1. What is the molecular shape of a water molecule?
, A. Linear
B. Tetrahedral
C. Bent
D. Trigonal planar
Rationale: A water molecule has a bent shape due to the two lone pairs of electrons on the
oxygen atom, which repel the bonding pairs and push them closer together. The bond angle
is approximately 104.5 degrees.
2. The bond angle in a water molecule is approximately:
A. 90 degrees
B. 104.5 degrees
C. 109.5 degrees
D. 120 degrees
Rationale: The bond angle in water is 104.5 degrees, a consequence of its bent shape
caused by the two lone pairs of electrons on the oxygen atom.
3. What factor contributes to the bent shape of a water molecule?
A. The dipole arrows in a water molecule
B. The unshared electron pairs on the oxygen atom
C. The electronegativity difference between hydrogen and oxygen
D. The unequal electron sharing between hydrogen and oxygen
Rationale: The bent shape of water is due to the two lone (unshared) pairs of electrons on
the oxygen atom. These lone pairs repel the bonding pairs, compressing the bond angle.
4. Which of the following contributes to water's unique properties?
A. The bent geometry of the molecule
B. The polarity of the O-H bonds
Learning Latest 2026/2027 Update | Water, pH, Buffers
& Aqueous Systems | Bold Answers with
Explanations
Introduction
This practice exam is designed for students preparing for the CHEM 210 Module 2
Exam at Portage Learning. Module 2 focuses on fundamental biochemistry concepts
related to water and aqueous systems, including:
Water Chemistry – Molecular shape, polarity, hydrogen bonding
pH & Buffers – Autoionization of water, acid-base equilibrium
Intermolecular Forces – Hydrogen bonds, dipole-dipole interactions, London
dispersion forces
Thermodynamics – Enthalpy, entropy, Gibbs free energy
Acid Strength & pKa – Ka, pKa calculations, acid strength comparisons
Each question includes the correct answer in bold and a detailed rationale based on the
Portage Learning curriculum.
Section 1: Water Chemistry & Molecular Properties (Questions 1-20)
1. What is the molecular shape of a water molecule?
, A. Linear
B. Tetrahedral
C. Bent
D. Trigonal planar
Rationale: A water molecule has a bent shape due to the two lone pairs of electrons on the
oxygen atom, which repel the bonding pairs and push them closer together. The bond angle
is approximately 104.5 degrees.
2. The bond angle in a water molecule is approximately:
A. 90 degrees
B. 104.5 degrees
C. 109.5 degrees
D. 120 degrees
Rationale: The bond angle in water is 104.5 degrees, a consequence of its bent shape
caused by the two lone pairs of electrons on the oxygen atom.
3. What factor contributes to the bent shape of a water molecule?
A. The dipole arrows in a water molecule
B. The unshared electron pairs on the oxygen atom
C. The electronegativity difference between hydrogen and oxygen
D. The unequal electron sharing between hydrogen and oxygen
Rationale: The bent shape of water is due to the two lone (unshared) pairs of electrons on
the oxygen atom. These lone pairs repel the bonding pairs, compressing the bond angle.
4. Which of the following contributes to water's unique properties?
A. The bent geometry of the molecule
B. The polarity of the O-H bonds
