MCQs on pH and Buffer Solutions for ICAR (SRF or JRF) /ASRB /CSIR NET/BET Exams #1

 

1. Which of the following combinations cannot produce a buffer solution?
   (A) HNO₂ and NaNO₂
   (B) HCN and NaCN
   (C) HClO₄ and NaClO₄
   (D) NH₃ and (NH₄)₂SO₄

2. What is the pH of a solution composed of 0.20 M NH₃ and 0.15 M NH₄Cl?
   (A) 2.15
   (B) 4.62
   (C) 8.26
   (D) 9.38

3. Calculate the ratio [CH₃COOH]/[NaCH₃COO] that gives a solution with pH = 5.00:
   (A) 0.28
   (B) 0.36
   (C) 0.44
   (D) 0.56

4. Consider a solution 0.10 M in CH₃COOH and 0.20 M in NaCH₃COO. Which of the following is true?
   (A) If a small amount of NaOH is added, the pH decreases very slightly.
   (B) If NaOH is added, the OH⁻ ions react with the CH₃COO⁻ ions.
   (C) If a small amount of HCl is added, the pH decreases very slightly.
   (D) If HCl is added, the H⁺ ions react with CH₃COOH ions.

5. A buffer was prepared by mixing 1.00 mole of ammonia and 1.00 mole of ammonium chloride in 1 L. To 500 mL of this solution was added 30.0 mL of 1.00 M NaOH. The pH is:
   (A) 8.96
   (B) 9.83
   (C) 9.31
   (D) 9.11

6. How many grams of NaF would have to be added to 2.00 L of 0.100 M HF to yield a solution with pH = 4.00?
   (A) 300 g
   (B) 36 g
   (C) 0.84 g
   (D) 60 g

7. Calculate the pH when mixing:

   • 35 mL of 0.20 M formic acid

   • 55 mL of 0.10 M sodium formate

   • 110 mL of water
     (A) 3.64
     (B) 3.11
     (C) 4.58
     (D) 3.39

8. Calculate the pH after adding 20.0 mL of 0.100 M NaOH to 30.0 mL of 0.100 M HNO₃:
   (A) 1.35
   (B) 1.70
   (C) 1.95
   (D) 2.52

9. Which of the following is a weak acid?
   (A) HNO₃
   (B) HI
   (C) HBr
   (D) HF

10. In a sample of pure water, which statement is always true under all temperature and pressure conditions?
    (A) [H₃O⁺] = 1.0 × 10⁻⁷ M
    (B) [OH⁻] = 1.0 × 10⁻⁷ M
    (C) pH = 7.0
    (D) [H₃O⁺] = [OH⁻]

11. If K_w = 2.9 × 10⁻¹⁵ at 10°C, what is the pH of pure water?
    (A) 6.72
    (B) 7.00
    (C) 7.27
    (D) 7.53

12. The pOH of a solution of NaOH is 11.30. What is the [H⁺]?
    (A) 2.0 × 10⁻³
    (B) 2.5 × 10⁻³
    (C) 5.0 × 10⁻¹²
    (D) 4.0 × 10⁻¹²

13. Approximate pH of a solution labeled 6 × 10⁻⁵ M HBr:
    (A) 4.2
    (B) 4.5
    (C) 5.8
    (D) 9.8

14. A solution in which [H⁺] = 10⁻⁸ M has a pH of ___ and is ___.
    (A) 8, acidic
    (B) 6, basic
    (C) -6, basic
    (D) 8, basic

15. Which solution has the lowest pH at 25°C?
    (A) 0.2 M NaOH
    (B) 0.2 M hypochlorous acid
    (C) 0.2 M ammonia
    (D) 0.2 M benzoic acid