Hydrogen Ion Concentration pH Scale and Buffer Solution MCQs
31. Which of the following will decrease the pH of a buffer solution?
- A) Adding more weak acid
- B) Adding more salt of the weak acid
- C) Adding a strong base
- D) Adding a strong acid
- Answer: D
32. The relationship between pKa and pH in a buffer solution is best described by:
- A) pKa + pH = 14
- B) pKa = pH + log([A⁻]/[HA])
- C) pH = pKa + log([A⁻]/[HA])
- D) pH = pKa – log([HA]/[A⁻])
- Answer: C
33. If the concentration of the conjugate base in a buffer solution is much greater than that of the weak acid, the pH will be:
- A) Higher than pKa
- B) Lower than pKa
- C) Equal to pKa
- D) Cannot be determined
- Answer: A
34. Which of the following is an example of a physiological buffer?
- A) Acetic acid and sodium acetate
- B) Carbonic acid and bicarbonate
- C) Phosphate buffer
- D) Both B and C
- Answer: D
35. A strong acid will completely dissociate in solution, while a weak acid:
- A) Does not dissociate at all
- B) Partially dissociates
- C) Dissociates completely
- D) Cannot be measured
- Answer: B
36. Which of the following statements is true regarding pH indicators?
- A) They change color at specific pH ranges.
- B) They are always neutral.
- C) They do not change in acidic or basic conditions.
- D) They can only be used in titrations.
- Answer: A
37. The pH of a solution can be adjusted using:
- A) Weak acids and their salts
- B) Strong acids and bases
- C) Both A and B
- D) None of the above
- Answer: C
38. In an acidic solution, which of the following is true?
- A) [H⁺] > [OH⁻]
- B) [H⁺] < [OH⁻]
- C) [H⁺] = [OH⁻]
- D) [H⁺] is irrelevant
- Answer: A
39. A solution with a pH of 5 has how many times more hydrogen ions than a solution with a pH of 7?
- A) 10 times
- B) 100 times
- C) 1000 times
- D) 1 time
- Answer: B
40. What happens to the pH of a buffer solution when a strong acid is added?
- A) The pH increases significantly
- B) The pH decreases significantly
- C) The pH remains relatively stable
- D) The buffer is neutralized
- Answer: C