CHEM 210 Biochemistry Module 1: Water, pH, and Buffers 2026/2027
UPDATE
1. Which of the following describes the geometry of a water molecule?
A. Linear
B. Trigonal planar
C. Bent/Angular
D. Tetrahedral
Answer: C
Rationale: Water has a bent geometry due to the two lone pairs of electrons on the oxygen
atom that repel the bonding pairs.
2. What is the maximum number of hydrogen bonds a single water molecule
can form?
A. 4
B. 3
C. 2
D. 6
Answer: A
Rationale: A water molecule can form four hydrogen bonds: two through its hydrogen
atoms and two through the lone pairs on oxygen.
,3. Which property of water allows it to resist rapid changes in temperature?
A. Low density when frozen
B. High specific heat capacity
C. High surface tension
D. Neutral pH
Answer: B
Rationale: High specific heat capacity allows water to absorb or release large amounts of
heat with minimal temperature change.
4. The hydrophobic effect is primarily driven by:
A. Strong attraction between nonpolar molecules
B. Covalent bonding between water and oil
C. An increase in water entropy
D. Ionic interactions
Answer: C
Rationale: Water molecules form ordered cages around nonpolar solutes; when nonpolar
solutes aggregate, water is released, increasing entropy.
5. If the [H+] of a solution is 1 x 10^-5 M, what is the pH?
A. -5
B. 9
C. 5
D. 14
Answer: C
Rationale: pH is calculated as -log[H+]. -log(10^-5) = 5.
, 6. What is the pH of a solution with an [OH-] concentration of 1 x 10^-4 M?
A. 10
B. 7
C. 4
D. 14
Answer: A
Rationale: pOH = -log(10^-4) = 4. Since pH + pOH = 14, pH = 14 - 4 = 10.
7. A Bronsted-Lowry acid is defined as a molecule that:
A. Accepts a proton
B. Donates a proton
C. Accepts an electron pair
D. Donates a hydroxide ion
Answer: B
Rationale: Bronsted-Lowry acids are proton (H+) donors.
8. Which of the following is a characteristic of a strong acid?
A. It has a high pKa value
B. It dissociates completely in water
C. It does not dissociate in water
D. It acts as a buffer at pH 7
Answer: B
Rationale: Strong acids dissociate fully into their constituent ions in aqueous solution.
UPDATE
1. Which of the following describes the geometry of a water molecule?
A. Linear
B. Trigonal planar
C. Bent/Angular
D. Tetrahedral
Answer: C
Rationale: Water has a bent geometry due to the two lone pairs of electrons on the oxygen
atom that repel the bonding pairs.
2. What is the maximum number of hydrogen bonds a single water molecule
can form?
A. 4
B. 3
C. 2
D. 6
Answer: A
Rationale: A water molecule can form four hydrogen bonds: two through its hydrogen
atoms and two through the lone pairs on oxygen.
,3. Which property of water allows it to resist rapid changes in temperature?
A. Low density when frozen
B. High specific heat capacity
C. High surface tension
D. Neutral pH
Answer: B
Rationale: High specific heat capacity allows water to absorb or release large amounts of
heat with minimal temperature change.
4. The hydrophobic effect is primarily driven by:
A. Strong attraction between nonpolar molecules
B. Covalent bonding between water and oil
C. An increase in water entropy
D. Ionic interactions
Answer: C
Rationale: Water molecules form ordered cages around nonpolar solutes; when nonpolar
solutes aggregate, water is released, increasing entropy.
5. If the [H+] of a solution is 1 x 10^-5 M, what is the pH?
A. -5
B. 9
C. 5
D. 14
Answer: C
Rationale: pH is calculated as -log[H+]. -log(10^-5) = 5.
, 6. What is the pH of a solution with an [OH-] concentration of 1 x 10^-4 M?
A. 10
B. 7
C. 4
D. 14
Answer: A
Rationale: pOH = -log(10^-4) = 4. Since pH + pOH = 14, pH = 14 - 4 = 10.
7. A Bronsted-Lowry acid is defined as a molecule that:
A. Accepts a proton
B. Donates a proton
C. Accepts an electron pair
D. Donates a hydroxide ion
Answer: B
Rationale: Bronsted-Lowry acids are proton (H+) donors.
8. Which of the following is a characteristic of a strong acid?
A. It has a high pKa value
B. It dissociates completely in water
C. It does not dissociate in water
D. It acts as a buffer at pH 7
Answer: B
Rationale: Strong acids dissociate fully into their constituent ions in aqueous solution.
