Questions on Strong and Weak Acids and Acid Ionization Constant (Ka) and Base Ionization Constant (Kb)
Multiple-Choice Questions
1. Which of the following acids is considered a strong acid?
A) Acetic acid (CH3COOH)
B) Hydrochloric acid (HCl)
C) Formic acid (HCOOH)
D) Carbonic acid (H2CO3)
E) Hydrofluoric acid (HF)
2. What does a high value of Ka indicate about an acid?
A) The acid is very weak
B) The acid partially ionizes in solution
C) The acid strongly ionizes in solution
D) The acid is neutral
E) The acid has a very high molecular weight
3. Which of the following is NOT a characteristic of weak acids?
A) They partially ionize in aqueous solution
B) They have a low Ka value
C) They dissociate completely in solution
D) They usually have a higher pH than strong acids at the same concentration
E) They have a higher conjugate base concentration in equilibrium
4. Which expression represents the acid ionization constant, Ka, for a generic acid HA?
A) Ka = [HA][H3O+] / [A^-]
B) Ka = [A^-][H3O+] / [HA]
C) Ka = [HA] / [A^-][H3O+]
D) Ka = [H2O][HA] / [A^-]
E) Ka = [A^-] / [HA][H3O+]
5. If the Ka of an acid is 1.0 × 10⁻⁵, what can you say about its strength?
A) It is a strong acid
B) It is a weak acid
C) It is neutral
D) It is a strong base
E) It is amphoteric
6. Which of the following is a weak acid?
A) HCl
B) HNO3
C) H2SO4
D) HF
E) HBr
7. The base ionization constant (Kb) is related to which of the following?
A) The dissociation of a strong acid
B) The ionization of water
C) The ionization of a base in water
D) The neutralization reaction between acid and base
E) The oxidation of a base
8. For a conjugate acid-base pair, the relationship between Ka and Kb is:
A) Ka + Kb = Kw
B) Ka × Kb = Kw
C) Ka / Kb = Kw
D) Ka - Kb = Kw
E) Ka = Kb
9. What is the value of Kw at 25°C?
A) 1 × 10⁻⁷
B) 1 × 10⁻¹⁴
C) 1 × 10⁻⁵
D) 1 × 10⁻¹²
E) 1 × 10⁻³
10. If the Kb of a base is 1.0 × 10⁻⁹, what is the Ka of its conjugate acid at 25°C?
A) 1.0 × 10⁻⁵
B) 1.0 × 10⁻⁷
C) 1.0 × 10⁻⁴
D) 1.0 × 10⁻⁶
E) 1.0 × 10⁻¹⁰
11. Which species is considered the conjugate base of the acid H2SO4?
A) SO4²⁻
B) HSO4⁻
C) H3O+
D) SO3²⁻
E) OH⁻
12. When a strong acid dissolves in water, what is the approximate concentration of H3O+ ions relative to the initial acid concentration?
A) Much less than initial acid concentration
B) Approximately equal to the initial acid concentration
C) Zero
D) Twice the initial acid concentration
E) Less than half the initial acid concentration
13. Which acid has the lowest Ka value (weakest acid) among the following?
A) HClO4 (perchloric acid)
B) HNO3 (nitric acid)
C) CH3COOH (acetic acid)
D) H2SO4 (sulfuric acid)
E) HBr (hydrobromic acid)
14. A solution with pH = 3 contains mostly:
A) Strong acid
B) Weak acid
C) Hydronium ions at 1 × 10⁻³ M
D) Hydroxide ions at 1 × 10⁻³ M
E) Neutral water
15. If the pKa of an acid is 4.75, what is the Ka?
A) 1.78 × 10⁻⁵
B) 4.75 × 10⁻⁴
C) 2.34 × 10⁻⁴
D) 5.62 × 10⁻⁵
E) 1.0 × 10⁻⁷
16. Which statement is true about a strong base?
A) It partially ionizes in solution
B) It has a low Kb value
C) It completely ionizes in solution
D) It has no conjugate acid
E) It cannot accept protons
17. What does the term "percent ionization" refer to in the context of weak acids?
A) The percent of acid molecules that react with the base
B) The percent of acid molecules that dissociate into ions in solution
C) The percent of base molecules that dissociate into ions in solution
D) The percent of water molecules ionized
E) The percent of acid molecules that remain undissociated
18. Which of the following acids is diprotic?
A) HCl
B) H2SO4
C) HNO3
D) CH3COOH
E) HF
19. In the equation: HA ⇌ H+ + A⁻, which direction does the equilibrium favor for a weak acid?
A) Towards the right (products)
B) Towards the left (reactants)
C) Completely to the right
D) Completely to the left
E) Equal amounts on both sides
20. What is the conjugate acid of the base NH3 (ammonia)?
A) NH2⁻
B) NH4⁺
C) NH3⁻
D) NH4OH
E) NO3⁻
- Questions on Self-Ionization of Water (Kw)
- Questions on pH and Calculating pH
- Questions on pOH Scale and Calculations
Answers
1. B) Hydrochloric acid (HCl)
2. C) The acid strongly ionizes in solution
3. C) They dissociate completely in solution
4. B) Ka = [A^-][H3O+] / [HA]
5. B) It is a weak acid
6. D) HF
7. C) The ionization of a base in water
8. B) Ka × Kb = Kw
9. B) 1 × 10⁻¹⁴
10. A) 1.0 × 10⁻⁵
11. B) HSO4⁻
12. B) Approximately equal to the initial acid concentration
13. C) CH3COOH (acetic acid)
14. C) Hydronium ions at 1 × 10⁻³ M
15. A) 1.78 × 10⁻⁵
16. C) It completely ionizes in solution
17. B) The percent of acid molecules that dissociate into ions in solution
18. B) H2SO4
19. B) Towards the left (reactants)
20. B) NH4⁺
Dive into the groundbreaking science of neurotransmitters—your brain’s invisible architects—in Chemical Harmony: How Neurotransmitters Shape Our Lives (2025). This meticulously researched book reveals how serotonin, dopamine, GABA, and other brain chemicals silently orchestrate every aspect of your existence, from decision-making and relationships to mental health and emotional resilience.Click here to buy
Share Online!
