CHEM 121 MODULE 7 EXAM – 200 PRACTICE QUESTIONS |
PORTAGE LEARNING
SECTION 1: ACIDS, BASES & CONJUGATES (Questions 1–25)
1. According to the Arrhenius definition, an acid is a substance that:
- A) Donates a proton (H⁺) in aqueous solution
- B) Accepts a proton in aqueous solution
- C) Increases the concentration of H⁺ ions in aqueous solution
- D) Increases the concentration of OH⁻ ions in aqueous solution
Answer: C
Explanation: Arrhenius defined an acid as a substance that produces H⁺ (or H₃O⁺) in aqueous solution.
Option A is the Brønsted‑Lowry definition.
2. Which of the following is a Brønsted‑Lowry base?
- A) HCl
- B) NH₃
- C) H₂SO₄
- D) CH₃COOH
Answer: B
Explanation: NH₃ accepts a proton (H⁺) to form NH₄⁺, making it a Brønsted‑Lowry base. HCl, H₂SO₄, and
CH₃COOH are acids (proton donors).
3. The conjugate acid of NH₃ is:
- A) NH₂⁻
- B) NH₄⁺
- C) N³⁻
,- D) HNO₃
Answer: B
Explanation: NH₃ accepts a proton (H⁺) to form NH₄⁺, its conjugate acid.
4. The conjugate base of H₂O is:
- A) H₃O⁺
- B) OH⁻
- C) O²⁻
- D) H₂O₂
Answer: B
Explanation: H₂O donates a proton (H⁺) to form OH⁻, its conjugate base.
5. Which of the following is a strong acid?
- A) HCl
- B) CH₃COOH
- C) H₂CO₃
- D) HF
Answer: A
Explanation: HCl is a strong acid (completely dissociates in water). CH₃COOH, H₂CO₃, and HF are weak
acids.
6. Which of the following is a strong base?
- A) NH₃ (ammonia)
- B) NaOH (sodium hydroxide)
- C) CH₃NH₂ (methylamine)
- D) CaCO₃ (calcium carbonate)
,Answer: B
Explanation: NaOH is a strong base (completely dissociates to Na⁺ and OH⁻). NH₃ and CH₃NH₂ are weak
bases.
7. The [H⁺] in a 0.10 M HCl solution is:
- A) 0.10 M
- B) 1.0 × 10⁻¹³ M
- C) 1.0 × 10⁻¹ M
- D) Both A and C
Answer: D
Explanation: HCl is a strong acid, so [H⁺] = 0.10 M = 1.0 × 10⁻¹ M.
8. The pH of a 0.010 M HCl solution is:
- A) 1
- B) 2
- C) 3
- D) 12
Answer: B
Explanation: [H⁺] = 0.010 M = 10⁻² M, pH = 2.
9. The pH of a solution with [H⁺] = 1.0 × 10⁻³ M is:
- A) 1
- B) 3
- C) 7
- D) 11
, Answer: B
Explanation: pH = –log[H⁺] = –log(1.0 × 10⁻³) = 3.0.
10. The pOH of a solution with [OH⁻] = 1.0 × 10⁻⁵ M is:
- A) 5
- B) 9
- C) 7
- D) 14
Answer: A
Explanation: pOH = –log[OH⁻] = –log(1.0 × 10⁻⁵) = 5.0.
11. What is the pH of a solution with [OH⁻] = 1.0 × 10⁻⁴ M? (K_w = 1.0 × 10⁻¹⁴)
- A) 4
- B) 10
- C) 14
- D) 7
Answer: B
Explanation: pOH = –log(1.0 × 10⁻⁴) = 4.0; pH = 14.0 – pOH = 10.0.
12. A solution with pH = 2.0 has [H⁺] equal to:
- A) 2.0 M
- B) 1.0 × 10⁻² M
- C) 1.0 × 10⁻¹² M
- D) 2.0 × 10⁻¹⁴ M
Answer: B
Explanation: [H⁺] = 10⁻pH = 10⁻² = 1.0 × 10⁻² M.
PORTAGE LEARNING
SECTION 1: ACIDS, BASES & CONJUGATES (Questions 1–25)
1. According to the Arrhenius definition, an acid is a substance that:
- A) Donates a proton (H⁺) in aqueous solution
- B) Accepts a proton in aqueous solution
- C) Increases the concentration of H⁺ ions in aqueous solution
- D) Increases the concentration of OH⁻ ions in aqueous solution
Answer: C
Explanation: Arrhenius defined an acid as a substance that produces H⁺ (or H₃O⁺) in aqueous solution.
Option A is the Brønsted‑Lowry definition.
2. Which of the following is a Brønsted‑Lowry base?
- A) HCl
- B) NH₃
- C) H₂SO₄
- D) CH₃COOH
Answer: B
Explanation: NH₃ accepts a proton (H⁺) to form NH₄⁺, making it a Brønsted‑Lowry base. HCl, H₂SO₄, and
CH₃COOH are acids (proton donors).
3. The conjugate acid of NH₃ is:
- A) NH₂⁻
- B) NH₄⁺
- C) N³⁻
,- D) HNO₃
Answer: B
Explanation: NH₃ accepts a proton (H⁺) to form NH₄⁺, its conjugate acid.
4. The conjugate base of H₂O is:
- A) H₃O⁺
- B) OH⁻
- C) O²⁻
- D) H₂O₂
Answer: B
Explanation: H₂O donates a proton (H⁺) to form OH⁻, its conjugate base.
5. Which of the following is a strong acid?
- A) HCl
- B) CH₃COOH
- C) H₂CO₃
- D) HF
Answer: A
Explanation: HCl is a strong acid (completely dissociates in water). CH₃COOH, H₂CO₃, and HF are weak
acids.
6. Which of the following is a strong base?
- A) NH₃ (ammonia)
- B) NaOH (sodium hydroxide)
- C) CH₃NH₂ (methylamine)
- D) CaCO₃ (calcium carbonate)
,Answer: B
Explanation: NaOH is a strong base (completely dissociates to Na⁺ and OH⁻). NH₃ and CH₃NH₂ are weak
bases.
7. The [H⁺] in a 0.10 M HCl solution is:
- A) 0.10 M
- B) 1.0 × 10⁻¹³ M
- C) 1.0 × 10⁻¹ M
- D) Both A and C
Answer: D
Explanation: HCl is a strong acid, so [H⁺] = 0.10 M = 1.0 × 10⁻¹ M.
8. The pH of a 0.010 M HCl solution is:
- A) 1
- B) 2
- C) 3
- D) 12
Answer: B
Explanation: [H⁺] = 0.010 M = 10⁻² M, pH = 2.
9. The pH of a solution with [H⁺] = 1.0 × 10⁻³ M is:
- A) 1
- B) 3
- C) 7
- D) 11
, Answer: B
Explanation: pH = –log[H⁺] = –log(1.0 × 10⁻³) = 3.0.
10. The pOH of a solution with [OH⁻] = 1.0 × 10⁻⁵ M is:
- A) 5
- B) 9
- C) 7
- D) 14
Answer: A
Explanation: pOH = –log[OH⁻] = –log(1.0 × 10⁻⁵) = 5.0.
11. What is the pH of a solution with [OH⁻] = 1.0 × 10⁻⁴ M? (K_w = 1.0 × 10⁻¹⁴)
- A) 4
- B) 10
- C) 14
- D) 7
Answer: B
Explanation: pOH = –log(1.0 × 10⁻⁴) = 4.0; pH = 14.0 – pOH = 10.0.
12. A solution with pH = 2.0 has [H⁺] equal to:
- A) 2.0 M
- B) 1.0 × 10⁻² M
- C) 1.0 × 10⁻¹² M
- D) 2.0 × 10⁻¹⁴ M
Answer: B
Explanation: [H⁺] = 10⁻pH = 10⁻² = 1.0 × 10⁻² M.
