{"id":12817,"date":"2025-09-23T12:57:38","date_gmt":"2025-09-23T11:57:38","guid":{"rendered":"https:\/\/mcqsadda.com\/?p=12817"},"modified":"2025-10-22T10:36:57","modified_gmt":"2025-10-22T09:36:57","slug":"concepts-of-ph-scale-top-100-mcqs-with-answer-and-explanation","status":"publish","type":"post","link":"https:\/\/mcqsadda.com\/index.php\/2025\/09\/23\/concepts-of-ph-scale-top-100-mcqs-with-answer-and-explanation\/","title":{"rendered":"Concepts of pH scale Top 100 MCQs With Answer and Explanation"},"content":{"rendered":"\n

1. pH is defined as:<\/strong><\/mark>
A) log [H\u207a]
B) \u2013log [H\u207a]
C) log [OH\u207b]
D) \u2013log [OH\u207b]
Answer:<\/strong> B
Explanation:<\/strong> pH = \u2013log\u2081\u2080[H\u207a], where [H\u207a] is the hydrogen ion concentration in mol\/L.<\/p>\n\n\n\n

2. The pH of a neutral solution at 25 \u00b0C is:<\/strong>
<\/mark>A) 0
B) 7
C) 14
D) 1
Answer:<\/strong> B
Explanation:<\/strong> At 25 \u00b0C, pure water has [H\u207a] = 1 \u00d7 10\u207b\u2077 \u2192 pH = 7.<\/p>\n\n\n\n

3. The pH of 0.001 M HCl solution is:
<\/mark><\/strong>A) 1
B) 2
C) 3
D) 4
Answer:<\/strong> C
Explanation:<\/strong> pH = \u2013log [H\u207a] = \u2013log (10\u207b\u00b3) = 3.<\/p>\n\n\n\n

4. Which solution has the lowest pH?
<\/mark><\/strong>A) 0.01 M HCl
B) 0.001 M HCl
C) Pure water
D) 0.01 M NaOH
Answer:<\/strong> A
Explanation:<\/strong> Higher [H\u207a] \u2192 lower pH. 0.01 M HCl has pH = 2, the lowest here.<\/p>\n\n\n\n

5. The pH of 0.01 M NaOH solution is:
<\/mark><\/strong>A) 12
B) 10
C) 2
D) 4
Answer:<\/strong> A
Explanation:<\/strong> [OH\u207b] = 0.01 = 10\u207b\u00b2 \u2192 pOH = 2 \u2192 pH = 14 \u2013 2 = 12.<\/p>\n\n\n\n

6. What is the pOH of a neutral solution at 25 \u00b0C?
<\/mark><\/strong>A) 0
B) 7
C) 14
D) 1
Answer:<\/strong> B
Explanation:<\/strong> For neutral water, [OH\u207b] = 10\u207b\u2077 \u2192 pOH = 7.<\/p>\n\n\n\n

7. Which formula relates pH and pOH?<\/strong>
<\/mark>A) pH + pOH = 0
B) pH + pOH = 7
C) pH + pOH = 10
D) pH + pOH = 14
Answer:<\/strong> D
Explanation:<\/strong> At 25 \u00b0C, pH + pOH = 14 (since Kw = 10\u207b\u00b9\u2074).<\/p>\n\n\n\n

8. The solution with pH = 1 is:<\/strong>
<\/mark>A) Strongly acidic
B) Weakly acidic
C) Neutral
D) Basic
Answer:<\/strong> A
Explanation:<\/strong> pH < 7 \u2192 acidic. Very low pH (1) \u2192 strongly acidic.<\/p>\n\n\n\n

9. The solution with pH = 9 is:<\/mark>
<\/strong>1<\/a><\/sup>A) Strongly acidic
B) Weakly acidic
C) Weakly basic
D) Strongly basic
Answer:<\/strong> C
Explanation:<\/strong> pH > 7 \u2192 basic. Since it\u2019s near 7, it\u2019s weakly basic.<\/p>\n\n\n\n

10. The pH of a strong acid increases when:<\/mark><\/strong>
A) Diluted with water
B) Heated
C) Mixed with strong base
D) Both A and C
Answer:<\/strong> D
Explanation:<\/strong> Dilution reduces [H\u207a], neutralization with base consumes H\u207a \u2192 pH increases.<\/p>\n\n\n\n

11. Which indicator is used to measure pH around 7?
<\/mark><\/strong>A) Phenolphthalein
B) Methyl orange
C) Bromothymol blue
D) Litmus
Answer:<\/strong> C
Explanation:<\/strong> Bromothymol blue has transition range 6.0\u20137.6 \u2192 suitable near neutral pH.<\/p>\n\n\n\n

12. Which indicator is suitable for strong acid vs strong base titration?
<\/mark><\/strong>A) Phenolphthalein
B) Methyl orange
C) Either A or B
D) None
Answer:<\/strong> C
Explanation:<\/strong> Strong acid\u2013strong base equivalence point at pH \u2248 7 \u2192 either phenolphthalein or methyl orange can work.<\/p>\n\n\n\n

13. pH paper turns red in:
<\/mark><\/strong>A) Acidic solution
B) Basic solution
C) Neutral solution
D) Salt solution
Answer:<\/strong> A
Explanation:<\/strong> Acids turn pH paper red.<\/p>\n\n\n\n

14. The pH of gastric juice is about:
<\/mark><\/strong>A) 7
B) 1\u20132
C) 4\u20135
D) 9
Answer:<\/strong> B
Explanation:<\/strong> Gastric juice contains HCl, pH \u2248 1\u20132.<\/p>\n\n\n\n

15. The pH of human blood is about:
<\/mark><\/strong>A) 4.5
B) 6.0
C) 7.4
D) 9.0
Answer:<\/strong> C
Explanation:<\/strong> Normal blood pH \u2248 7.35\u20137.45.<\/p>\n\n\n\n

16. The pH of saliva after meals is usually:
<\/mark><\/strong>A) 2
B) 4
C) 6.5\u20137.5
D) 9
Answer:<\/strong> C
Explanation:<\/strong> Saliva is slightly acidic to neutral (6.5\u20137.5).<\/p>\n\n\n\n

17. If [H\u207a] = 1 \u00d7 10\u207b\u2075 M, the pH is:
<\/mark><\/strong>A) 3
B) 5
C) 7
D) 9
Answer:<\/strong> B
Explanation:<\/strong> pH = \u2013log (10\u207b\u2075) = 5.<\/p>\n\n\n\n

18. If pH = 11, then [OH\u207b] is:
<\/mark><\/strong>A) 10\u207b\u00b3 M
B) 10\u207b\u00b2 M
C) 10\u207b\u00b9\u00b9 M
D) 10\u207b\u00b9 M
Answer:<\/strong> A
Explanation:<\/strong> pOH = 14 \u2013 11 = 3 \u2192 [OH\u207b] = 10\u207b\u00b3 M.<\/p>\n\n\n\n

19. The ionic product of water (Kw) at 25 \u00b0C is:
<\/mark><\/strong>A) 1 \u00d7 10\u207b\u2077
B) 1 \u00d7 10\u207b\u00b9\u2070
C) 1 \u00d7 10\u207b\u00b9\u2074
D) 1 \u00d7 10\u207b\u00b9\u2076
Answer:<\/strong> C
Explanation:<\/strong> Kw = [H\u207a][OH\u207b] = 1 \u00d7 10\u207b\u00b9\u2074 at 25 \u00b0C.<\/p>\n\n\n\n

20. When pH = 7 at 25 \u00b0C, then:
<\/mark><\/strong>A) Solution is neutral
B) [H\u207a] = [OH\u207b]
C) [H\u207a] = 10\u207b\u2077
D) All of the above
Answer:<\/strong> D
Explanation:<\/strong> Neutral solution has pH = 7, [H\u207a] = [OH\u207b] = 10\u207b\u2077.<\/p>\n\n\n\n

21. Which solution will have pH > 7?
<\/mark><\/strong>A) 0.1 M HCl
B) Pure water
C) 0.1 M NaOH
D) H\u2082SO\u2084
Answer:<\/strong> C
Explanation:<\/strong> NaOH is a strong base \u2192 pH > 7.<\/p>\n\n\n\n

22. If pH of solution decreases from 5 to 3, then [H\u207a]:
<\/mark><\/strong>A) Doubles
B) Increases by 100 times
C) Decreases by 10 times
D) Remains constant
Answer:<\/strong> B
Explanation:<\/strong> pH drop by 2 units \u2192 [H\u207a] increases by 10\u00b2 = 100 times.<\/p>\n\n\n\n

23. Which of the following is a weak acid?
<\/mark><\/strong>A) HCl
B) HNO\u2083
C) CH\u2083COOH
D) H\u2082SO\u2084
Answer:<\/strong> C
Explanation:<\/strong> Acetic acid (CH\u2083COOH) is weak, partially ionized.<\/p>\n\n\n\n

24. The pH scale usually ranges from:
<\/mark><\/strong>A) 0 to 7
B) \u20131 to 1
C) 0 to 14
D) 1 to 14
Answer:<\/strong> C
Explanation:<\/strong> Normal pH scale = 0\u201314, but can go below 0 or above 14 in extreme cases.<\/p>\n\n\n\n

25. Which device is used to measure pH accurately?
<\/mark><\/strong>A) Voltmeter
B) pH meter
C) Ammeter
D) Galvanometer
Answer:<\/strong> B
Explanation:<\/strong> A pH meter (glass electrode) measures pH accurately.<\/p>\n\n\n\n

26. The pH of 0.1 M HCl solution is:
<\/mark><\/strong>A) 0
B) 1
C) 2
D) 3
Answer:<\/strong> B
Explanation:<\/strong> pH = \u2013log [H\u207a] = \u2013log (0.1) = 1.<\/p>\n\n\n\n

27. The pH of 0.001 M NaOH solution is:
<\/mark><\/strong>A) 11
B) 12
C) 13
D) 3
Answer:<\/strong> A
Explanation:<\/strong> [OH\u207b] = 10\u207b\u00b3 \u2192 pOH = 3 \u2192 pH = 14 \u2013 3 = 11.<\/p>\n\n\n\n

28. A solution has [H\u207a] = 1 \u00d7 10\u207b\u2079 M. Its pH is:
<\/mark><\/strong>A) 9
B) 7
C) 5
D) 11
Answer:<\/strong> A
Explanation:<\/strong> pH = \u2013log [H\u207a] = \u2013log (10\u207b\u2079) = 9.<\/p>\n\n\n\n

29. The pH of 1 \u00d7 10\u207b\u2074 M HCl solution is:
<\/mark><\/strong>A) 2
B) 3
C) 4
D) 5
Answer:<\/strong> C
Explanation:<\/strong> pH = \u2013log (10\u207b\u2074) = 4.<\/p>\n\n\n\n

30. A solution with pH = 13 has [OH\u207b] = ?
<\/mark><\/strong>A) 10\u207b\u00b9
B) 10\u207b\u00b2
C) 10\u207b\u00b9\u00b3
D) 10\u207b\u2077
Answer:<\/strong> A
Explanation:<\/strong> pOH = 14 \u2013 13 = 1 \u2192 [OH\u207b] = 10\u207b\u00b9 M.<\/p>\n\n\n\n

31. Which salt solution has pH = 7?
<\/mark><\/strong>A) NaCl
B) NH\u2084Cl
C) CH\u2083COONa
D) Na\u2082CO\u2083
Answer:<\/strong> A
Explanation:<\/strong> NaCl is formed from strong acid (HCl) and strong base (NaOH) \u2192 neutral solution.<\/p>\n\n\n\n

32. Which salt solution is acidic?
<\/mark><\/strong>A) NaCl
B) NH\u2084Cl
C) Na\u2082CO\u2083
D) CH\u2083COONa
Answer:<\/strong> B
Explanation:<\/strong> NH\u2084Cl (from strong acid + weak base) hydrolyzes to give acidic solution.<\/p>\n\n\n\n

33. Which salt solution is basic?
<\/mark><\/strong>A) KCl
B) CH\u2083COONa
C) NH\u2084Cl
D) NaNO\u2083
Answer:<\/strong> B
Explanation:<\/strong> Sodium acetate (from strong base + weak acid) gives basic solution.<\/p>\n\n\n\n

34. A buffer solution is one which:
<\/mark><\/strong>A) Changes pH sharply with acid addition
B) Maintains nearly constant pH
C) Is neutral always
D) Has pH = 14
Answer:<\/strong> B
Explanation:<\/strong> Buffers resist change in pH upon addition of small amounts of acid\/base.<\/p>\n\n\n\n

35. Which is an example of acidic buffer?
<\/mark><\/strong>A) NH\u2084Cl + NH\u2084OH
B) CH\u2083COOH + CH\u2083COONa
C) H\u2082SO\u2084 + Na\u2082SO\u2084
D) NaOH + NaCl
Answer:<\/strong> B
Explanation:<\/strong> Acidic buffer = weak acid + its salt (e.g., CH\u2083COOH + CH\u2083COONa).<\/p>\n\n\n\n

36. Which is an example of basic buffer?
<\/mark><\/strong>A) HCl + NaCl
B) CH\u2083COOH + CH\u2083COONa
C) NH\u2084OH + NH\u2084Cl
D) H\u2082SO\u2084 + Na\u2082SO\u2084
Answer:<\/strong> C
Explanation:<\/strong> Basic buffer = weak base + its salt (e.g., NH\u2084OH + NH\u2084Cl).<\/p>\n\n\n\n

37. The Henderson\u2013Hasselbalch equation is used for:
<\/mark><\/strong>A) Determining Kw
B) Calculating pH of buffer
C) Measuring solubility
D) Determining \u0394G
Answer:<\/strong> B
Explanation:<\/strong> Henderson\u2013Hasselbalch equation:
pH = pKa + log([salt]\/[acid]).<\/p>\n\n\n\n

38. The pH of buffer solution made of 0.1 M CH\u2083COOH and 0.1 M CH\u2083COONa (Ka = 1.8 \u00d7 10\u207b\u2075) is:<\/mark><\/strong>
A) 4.74
B) 7
C) 3
D) 5.5
Answer:<\/strong> A
Explanation:<\/strong> pH = pKa + log([salt]\/[acid]) = 4.74 + log(1) = 4.74.<\/p>\n\n\n\n

39. In buffer solutions, maximum buffer capacity is when:
<\/mark><\/strong>A) [salt] > [acid]
B) [acid] > [salt]
C) [salt] = [acid]
D) pKa = 0
Answer:<\/strong> C
Explanation:<\/strong> Buffer is most effective when [acid] = [salt] \u2192 pH = pKa.<\/p>\n\n\n\n

40. The pH of blood is maintained by:
<\/mark><\/strong>A) HCl buffer
B) CH\u2083COOH buffer
C) H\u2082CO\u2083\/HCO\u2083\u207b buffer
D) NH\u2084Cl buffer
Answer:<\/strong> C
Explanation:<\/strong> Blood pH \u2248 7.4 is regulated by carbonic acid\/bicarbonate buffer.<\/p>\n\n\n\n

41. Which of the following can act as a buffer system?
<\/mark><\/strong>A) HNO\u2083 + NaNO\u2083
B) HCl + NaCl
C) CH\u2083COOH + CH\u2083COONa
D) NaOH + KOH
Answer:<\/strong> C
Explanation:<\/strong> Buffer = weak acid + its salt.<\/p>\n\n\n\n

42. When a small amount of acid is added to a buffer:
<\/mark><\/strong>A) pH decreases sharply
B) pH increases sharply
C) pH remains nearly constant
D) pH becomes neutral
Answer:<\/strong> C
Explanation:<\/strong> Buffer resists pH change.<\/p>\n\n\n\n

43. Which salt solution is alkaline due to hydrolysis?
<\/mark><\/strong>A) KNO\u2083
B) Na\u2082CO\u2083
C) NaCl
D) NH\u2084Cl
Answer:<\/strong> B
Explanation:<\/strong> Na\u2082CO\u2083 undergoes hydrolysis \u2192 basic solution.<\/p>\n\n\n\n

44. Which salt solution is acidic due to hydrolysis?
<\/mark><\/strong>A) NaCl
B) KNO\u2083
C) NH\u2084Cl
D) Na\u2082CO\u2083
Answer:<\/strong> C
Explanation:<\/strong> NH\u2084Cl hydrolyzes \u2192 acidic solution.<\/p>\n\n\n\n

45. Which of the following has pH > 7?
<\/mark><\/strong>A) HCl
B) NH\u2084Cl
C) Na\u2082CO\u2083
D) CH\u2083COOH
Answer:<\/strong> C
Explanation:<\/strong> Sodium carbonate solution is basic.<\/p>\n\n\n\n

46. The pH of 0.01 M NaOH solution at 25 \u00b0C is:
<\/mark><\/strong>A) 12
B) 2
C) 7
D) 10
Answer:<\/strong> A
Explanation:<\/strong> [OH\u207b] = 10\u207b\u00b2 \u2192 pOH = 2 \u2192 pH = 12.<\/p>\n\n\n\n

47. Which solution has highest [H\u207a]?<\/strong>
<\/mark>A) pH = 1
B) pH = 3
C) pH = 5
D) pH = 7
Answer:<\/strong> A
Explanation:<\/strong> Lower pH \u2192 higher [H\u207a].<\/p>\n\n\n\n

48. The pH of a solution is 6. The solution is:
<\/mark><\/strong>A) Strongly acidic
B) Weakly acidic
C) Neutral
D) Weakly basic
Answer:<\/strong> B
Explanation:<\/strong> pH slightly below 7 \u2192 weak acid.<\/p>\n\n\n\n

49. A solution with pH = 8 has [H\u207a] = ?<\/mark>
<\/strong>A) 10\u207b\u2076
B) 10\u207b\u2078
C) 10\u207b\u00b9\u2074
D) 10\u207b\u00b2
Answer:<\/strong> B
Explanation:<\/strong> pH = \u2013log [H\u207a] \u2192 [H\u207a] = 10\u207b\u2078.<\/p>\n\n\n\n

50. The pH of a buffer is equal to pKa of the acid when:
<\/strong><\/mark>A) [salt] = [acid]
B) [salt] > [acid]
C) [acid] > [salt]
D) Acid is strong
Answer:<\/strong> A
Explanation:<\/strong> From Henderson\u2013Hasselbalch equation:
pH = pKa + log(1) = pKa.<\/p>\n\n\n\n

51. The pH of lemon juice is about:
<\/mark><\/strong>A) 2
B) 5
C) 7
D) 9
Answer:<\/strong> A
Explanation:<\/strong> Lemon juice is strongly acidic (citric acid), pH \u2248 2.<\/p>\n\n\n\n

52. The pH of milk is about:
<\/mark><\/strong>A) 3.5
B) 6.5
C) 7.0
D) 8.5
Answer:<\/strong> B
Explanation:<\/strong> Fresh milk has slightly acidic pH \u2248 6.5.<\/p>\n\n\n\n

53. The pH of soap solution is usually:
<\/mark><\/strong>A) <7
B) =7
C) >7
D) Exactly 14
Answer:<\/strong> C
Explanation:<\/strong> Soap solution is basic, hence pH > 7.<\/p>\n\n\n\n

54. Tooth decay occurs when mouth pH falls below:
<\/mark><\/strong>A) 7.0
B) 6.0
C) 5.5
D) 9.0
Answer:<\/strong> C
Explanation:<\/strong> Below pH 5.5, enamel dissolves due to acid produced by bacteria.<\/p>\n\n\n\n

55. The pH of seawater is about:
<\/mark><\/strong>A) 5
B) 7
C) 8.2
D) 10
Answer:<\/strong> C
Explanation:<\/strong> Seawater is slightly alkaline, pH \u2248 8.2.<\/p>\n\n\n\n

56. Rainwater is naturally acidic due to:
<\/mark><\/strong>A) HNO\u2083
B) H\u2082SO\u2084
C) CO\u2082
D) NH\u2083
Answer:<\/strong> C
Explanation:<\/strong> CO\u2082 dissolves in rainwater forming carbonic acid \u2192 natural pH \u2248 5.6.<\/p>\n\n\n\n

57. Acid rain has pH value:<\/mark><\/strong>
A) >7
B) <5.6
C) Exactly 7
D) >10
Answer:<\/strong> B
Explanation:<\/strong> Acid rain occurs when pH < 5.6 (due to SO\u2082, NOx).<\/p>\n\n\n\n

58. The pH of human urine typically ranges between:<\/mark><\/strong>
A) 1\u20132
B) 3\u20134
C) 6\u20137
D) 10\u201311
Answer:<\/strong> C
Explanation:<\/strong> Urine is slightly acidic to neutral (\u2248 6.0\u20137.0).<\/p>\n\n\n\n

59. The optimum pH of pepsin enzyme is:
<\/mark><\/strong>A) 1\u20132
B) 4\u20135
C) 7
D) 9
Answer:<\/strong> A
Explanation:<\/strong> Pepsin works best in acidic gastric juice (pH 1\u20132).<\/p>\n\n\n\n

60. The optimum pH of trypsin enzyme is:
<\/mark><\/strong>A) 2
B) 5
C) 7\u20138
D) 10
Answer:<\/strong> C
Explanation:<\/strong> Trypsin acts in the intestine at alkaline pH (\u2248 7\u20138).<\/p>\n\n\n\n

61. The pH of blood is maintained close to 7.4 by:
<\/mark><\/strong>A) HCl buffer
B) CH\u2083COOH buffer
C) H\u2082CO\u2083\/HCO\u2083\u207b buffer
D) NaOH buffer
Answer:<\/strong> C
Explanation:<\/strong> The carbonic acid\u2013bicarbonate buffer controls blood pH.<\/p>\n\n\n\n

62. A drop in blood pH below 7.35 is called:
<\/mark><\/strong>A) Alkalosis
B) Acidosis
C) Neutralization
D) Buffering
Answer:<\/strong> B
Explanation:<\/strong> Blood pH <7.35 \u2192 acidosis (too acidic).<\/p>\n\n\n\n

63. A rise in blood pH above 7.45 is called:
<\/mark><\/strong>A) Alkalosis
B) Acidosis
C) Neutralization
D) Hydrolysis
Answer:<\/strong> A
Explanation:<\/strong> Blood pH >7.45 \u2192 alkalosis (too basic).<\/p>\n\n\n\n

64. Which organ regulates blood pH along with buffers?
<\/mark><\/strong>A) Heart
B) Kidney
C) Stomach
D) Liver
Answer:<\/strong> B
Explanation:<\/strong> Kidneys regulate pH by excreting H\u207a and reabsorbing HCO\u2083\u207b.<\/p>\n\n\n\n

65. Which environmental problem is directly related to low pH of rain?
<\/mark><\/strong>A) Greenhouse effect
B) Ozone hole
C) Acid rain
D) Eutrophication
Answer:<\/strong> C
Explanation:<\/strong> Acid rain is precipitation with low pH (<5.6).<\/p>\n\n\n\n

66. The pH of strong black coffee is about:
<\/mark><\/strong>A) 2.0
B) 4.5\u20135.0
C) 7.0
D) 9.0
Answer:<\/strong> B
Explanation:<\/strong> Coffee is mildly acidic, pH \u2248 4.5\u20135.0.<\/p>\n\n\n\n

67. The pH of bleach (NaOCl solution) is usually:
<\/mark><\/strong>A) 2
B) 5
C) 7
D) 12\u201313
Answer:<\/strong> D
Explanation:<\/strong> Bleach is strongly alkaline, pH 12\u201313.<\/p>\n\n\n\n

68. The logarithmic nature of pH scale means that a pH change of 1 unit corresponds to:
<\/mark><\/strong>A) 2-fold change in [H\u207a]
B) 5-fold change in [H\u207a]
C) 10-fold change in [H\u207a]
D) 100-fold change in [H\u207a]
Answer:<\/strong> C
Explanation:<\/strong> One pH unit change = 10\u00d7 change in hydrogen ion concentration.<\/p>\n\n\n\n

69. The pH of tomato juice is about:
<\/mark><\/strong>A) 2.0
B) 4.2
C) 6.0
D) 7.5
Answer:<\/strong> B
Explanation:<\/strong> Tomato juice is moderately acidic, pH \u2248 4.2.<\/p>\n\n\n\n

70. The pH of baking soda solution is around:
<\/mark><\/strong>A) 3
B) 7
C) 8\u20139
D) 12
Answer:<\/strong> C
Explanation:<\/strong> Baking soda (NaHCO\u2083) is weakly basic, pH \u2248 8\u20139.<\/p>\n\n\n\n

71. If a solution has [H\u207a] = 2 \u00d7 10\u207b\u00b3 M, its pH is:
<\/mark><\/strong>A) 2.7
B) 3.0
C) 5.0
D) 11.3
Answer:<\/strong> A
Explanation:<\/strong> pH = \u2013log (2 \u00d7 10\u207b\u00b3) \u2248 2.7.<\/p>\n\n\n\n

72. If a solution has pOH = 5, then its pH = ?
<\/mark><\/strong>A) 5
B) 7
C) 9
D) 14
Answer:<\/strong> C
Explanation:<\/strong> pH + pOH = 14 \u2192 pH = 14 \u2013 5 = 9.<\/p>\n\n\n\n

73. A solution has [OH\u207b] = 1 \u00d7 10\u207b\u2075 M. Its pH is:
<\/mark><\/strong>A) 5
B) 7
C) 9
D) 11
Answer:<\/strong> C
Explanation:<\/strong> pOH = 5 \u2192 pH = 14 \u2013 5 = 9.<\/p>\n\n\n\n

74. The pH of vinegar is about:
<\/mark><\/strong>A) 2\u20133
B) 5\u20136
C) 7
D) 9\u201310
Answer:<\/strong> A
Explanation:<\/strong> Vinegar contains acetic acid, pH \u2248 2\u20133.<\/p>\n\n\n\n

75. The pH of orange juice is approximately:
<\/mark><\/strong>A) 2.0
B) 3.5\u20134.0
C) 7.0
D) 9.0
Answer:<\/strong> B
Explanation:<\/strong> Orange juice is acidic (citric acid), pH \u2248 3.5\u20134.0.<\/p>\n\n\n\n

76. If pH of a solution is 2, the [H\u207a] concentration is:
<\/mark><\/strong>A) 1 \u00d7 10\u207b\u00b2 M
B) 1 \u00d7 10\u207b\u00b3 M
C) 1 \u00d7 10\u207b\u2074 M
D) 1 \u00d7 10\u207b\u2076 M
Answer:<\/strong> A
Explanation:<\/strong> pH = \u2013log[H\u207a] \u2192 [H\u207a] = 10\u207b\u00b2 M.<\/p>\n\n\n\n

77. The pH of a solution increases by 1 unit. This means the [H\u207a] concentration:
<\/mark><\/strong>A) Doubled
B) Increased 10\u00d7
C) Decreased 10\u00d7
D) Remained constant
Answer:<\/strong> C
Explanation:<\/strong> 1 pH unit rise = 10-fold decrease in [H\u207a].<\/p>\n\n\n\n

78. If pH of a solution is 10, then [OH\u207b] = ?
<\/strong><\/mark>A) 10\u207b\u00b9\u2070 M
B) 10\u207b\u2074 M
C) 10\u207b\u2075 M
D) 10\u207b\u00b3 M
Answer:<\/strong> B
Explanation:<\/strong> pH = 10 \u2192 pOH = 4 \u2192 [OH\u207b] = 10\u207b\u2074 M.<\/p>\n\n\n\n

79. The pH of 0.01 M H\u2082SO\u2084 solution is approximately:
<\/mark><\/strong>A) 1
B) 2
C) 12
D) 14
Answer:<\/strong> A
Explanation:<\/strong> Strong diprotic acid: [H\u207a] \u2248 2 \u00d7 0.01 = 0.02 \u2192 pH \u2248 1.7 (approximate to 1).<\/p>\n\n\n\n

80. Which of the following is used in industries to control pH?
<\/strong><\/mark>A) Buffers
B) Litmus paper
C) Distilled water
D) Phenolphthalein
Answer:<\/strong> A
Explanation:<\/strong> Buffer solutions are used in fermentation, pharmaceuticals, etc., to control pH.<\/p>\n\n\n\n

81. In soil chemistry, crop yield depends strongly on:
<\/mark><\/strong>A) Soil temperature
B) Soil pH
C) Soil pressure
D) Soil density
Answer:<\/strong> B
Explanation:<\/strong> Soil pH affects availability of nutrients to plants.<\/p>\n\n\n\n

82. The ideal pH range for most crops is:
<\/mark><\/strong>A) 2\u20133
B) 5.5\u20137.5
C) 8\u20139
D) 10\u201312
Answer:<\/strong> B
Explanation:<\/strong> Most crops grow best in slightly acidic to neutral soils.<\/p>\n\n\n\n

83. In swimming pools, the pH of water is maintained around:
<\/mark><\/strong>A) 4\u20135
B) 6\u20137
C) 7.2\u20137.8
D) 9\u201310
Answer:<\/strong> C
Explanation:<\/strong> Pool water is kept slightly basic to prevent irritation and control bacteria.<\/p>\n\n\n\n

84. The pH of shampoo is usually kept around:
<\/mark><\/strong>A) 2
B) 4\u20136
C) 7
D) 10
Answer:<\/strong> B
Explanation:<\/strong> Shampoos are mildly acidic (pH 4\u20136) to match scalp and maintain hair health.<\/p>\n\n\n\n

85. The pH of detergents is usually:
<\/mark><\/strong>A) Neutral
B) Slightly acidic
C) Basic
D) Zero
Answer:<\/strong> C
Explanation:<\/strong> Most detergents are alkaline to remove grease.<\/p>\n\n\n\n

86. The pH of lime water (Ca(OH)\u2082 solution) is about:
<\/mark><\/strong>A) 2
B) 7
C) 12
D) 14
Answer:<\/strong> C
Explanation:<\/strong> Lime water is a strong base, pH \u2248 12.<\/p>\n\n\n\n

87. A buffer solution is best when:
<\/mark><\/strong>A) [Salt] >> [Acid]
B) [Acid] >> [Salt]
C) [Salt] = [Acid]
D) Neither acid nor salt is present
Answer:<\/strong> C
Explanation:<\/strong> Buffer capacity is maximum when [acid] = [salt].<\/p>\n\n\n\n

88. Which food preservative works best in acidic medium (low pH)?
<\/mark><\/strong>A) Sodium chloride
B) Benzoic acid
C) Sugar
D) Baking soda
Answer:<\/strong> B
Explanation:<\/strong> Benzoic acid acts effectively as preservative at low pH.<\/p>\n\n\n\n

89. Which disease in humans is related to very low gastric pH?
<\/mark><\/strong>A) Acidity\/Ulcer
B) Diabetes
C) Hypertension
D) Tuberculosis
Answer:<\/strong> A
Explanation:<\/strong> Excess gastric acid (pH ~1) leads to acidity and ulcers.<\/p>\n\n\n\n

90. The pH of soap solution is generally:
<\/mark><\/strong>A) 4
B) 6
C) 8\u20139
D) 12
Answer:<\/strong> C
Explanation:<\/strong> Soap solution is weakly basic, pH 8\u20139.<\/p>\n\n\n\n

91. The pH of lime juice is:
<\/strong><\/mark>A) 2
B) 4
C) 7
D) 10
Answer:<\/strong> A
Explanation:<\/strong> Lime juice is strongly acidic, pH \u2248 2.<\/p>\n\n\n\n

92. Which instrument measures pH accurately?
<\/mark><\/strong>A) Ammeter
B) pH meter
C) Thermometer
D) Hygrometer
Answer:<\/strong> B
Explanation:<\/strong> A pH meter with glass electrode measures pH precisely.<\/p>\n\n\n\n

93. The pH of strong NaOH solution is close to:
<\/mark><\/strong>A) 0
B) 7
C) 14
D) 1
Answer:<\/strong> C
Explanation:<\/strong> Concentrated NaOH solution is highly basic, pH \u2248 14.<\/p>\n\n\n\n

94. The pH of saliva in the morning (before eating) is generally:
<\/mark><\/strong>A) 4\u20135
B) 6.5\u20137.5
C) 8\u20139
D) 10
Answer:<\/strong> B
Explanation:<\/strong> Saliva is near neutral in the morning, pH \u2248 6.5\u20137.5.<\/p>\n\n\n\n

95. If a solution has [H\u207a] = 1 \u00d7 10\u207b\u00b9\u00b2 M, its pH is:
<\/mark><\/strong>A) 2
B) 7
C) 10
D) 12
Answer:<\/strong> D
Explanation:<\/strong> pH = \u2013log (10\u207b\u00b9\u00b2) = 12.<\/p>\n\n\n\n

96. The pH of cola drinks is about:
<\/strong><\/mark>A) 1
B) 2.5
C) 7
D) 10
Answer:<\/strong> B
Explanation:<\/strong> Cola drinks are acidic due to carbonic and phosphoric acid, pH \u2248 2.5.<\/p>\n\n\n\n

97. Which chemical is used to neutralize acidic soils?<\/mark><\/strong>
A) NaCl
B) NaOH
C) CaCO\u2083
D) H\u2082SO\u2084
Answer:<\/strong> C
Explanation:<\/strong> Lime (CaCO\u2083) is used to raise soil pH (neutralize acidity).<\/p>\n\n\n\n

98. Which chemical is added to swimming pools to maintain pH?
<\/mark><\/strong>A) HCl
B) Na\u2082CO\u2083
C) H\u2082SO\u2084
D) CH\u2083COOH
Answer:<\/strong> B
Explanation:<\/strong> Sodium carbonate (soda ash) is added to keep pool water alkaline.<\/p>\n\n\n\n

99. At 25 \u00b0C, if pH = 6, then pOH = ?
<\/mark><\/strong>A) 6
B) 7
C) 8
D) 14
Answer:<\/strong> C
Explanation:<\/strong> pOH = 14 \u2013 pH = 14 \u2013 6 = 8.<\/p>\n\n\n\n

100. Which of the following statements about pH is correct?
<\/mark><\/strong>A) pH changes linearly with [H\u207a]
B) pH is logarithmic measure of [H\u207a]
C) Neutral solutions always have pH = 7 at any temperature
D) pH cannot be less than 0
Answer:<\/strong> B
Explanation:<\/strong> pH is logarithmic scale of [H\u207a]. At higher temperatures, neutral pH < 7, and very concentrated acids can have pH < 0.<\/p>\n","protected":false},"excerpt":{"rendered":"

1. pH is defined as:A) log [H\u207a]B) \u2013log [H\u207a]C) log [OH\u207b]D) \u2013log [OH\u207b]Answer: BExplanation: pH = \u2013log\u2081\u2080[H\u207a], where [H\u207a] is the hydrogen ion concentration in mol\/L. 2. The pH of a neutral solution at 25 \u00b0C is:A) 0B) 7C) 14D) 1Answer: BExplanation: At 25 \u00b0C, pure water has [H\u207a] = 1 \u00d7 10\u207b\u2077 \u2192 pH<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"[{\"id\":\"ae8161c6-ab6f-429f-89a4-85075b595182\",\"content\":\"\"}]"},"categories":[9],"tags":[16102,16103,16094,16101,15970,15886,15892,15876,15898,15901,15887,15899,15879,15883,10980,16104,16096,4029,15897,5649,5652,5623,16099,16098,15965,16093,15900,15896,16092,16095,15977,15894,16097,16100],"class_list":{"0":"post-12817","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-chemistry","7":"tag-acid-base-concepts","8":"tag-acid-base-indicators","9":"tag-acids-and-bases","10":"tag-buffer-solutions","11":"tag-chemistry-experiments","12":"tag-chemistry-formulas","13":"tag-chemistry-learning","14":"tag-chemistry-mcqs","15":"tag-chemistry-preparation-material","16":"tag-chemistry-questions-and-answers","17":"tag-chemistry-quiz","18":"tag-chemistry-revision","19":"tag-chemistry-study-material","20":"tag-competitive-exam-chemistry","21":"tag-concepts-of-ph-scale-top-100-mcqs-with-answer-and-explanation","22":"tag-environmental-chemistry","23":"tag-hydrogen-ion-concentration","24":"tag-mcqs-adda","25":"tag-mcqs-for-chemistry-exam","26":"tag-mcqs-for-pc-psi-sda-fda-pdo-vao-banking-kas-ias-ssc-gd-ssc-chsl-ssc-cgl-for-all-compitative-exams","27":"tag-mcqs-for-pc-psi-sda-fda-pdo-vao-banking-kas-ias-ssc-gd-ssc-chsl-ssc-cgl-for-all-compitative-examsin-kannada","28":"tag-mcqs-for-sda-fda-pdo-vao-banking-kas-ias-ssc-gd-ssc-chsl-ssc-cgl-for-all-compitative-exams","29":"tag-neutral-solution","30":"tag-ph-problems","31":"tag-ph-scale","32":"tag-poh","33":"tag-psc-chemistry-mcqs","34":"tag-ssc-chemistry-mcqs","35":"tag-strong-acids","36":"tag-strong-bases","37":"tag-titration","38":"tag-upsc-chemistry-mcqs","39":"tag-weak-acids","40":"tag-weak-bases"},"_links":{"self":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/12817","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/comments?post=12817"}],"version-history":[{"count":2,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/12817\/revisions"}],"predecessor-version":[{"id":12912,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/posts\/12817\/revisions\/12912"}],"wp:attachment":[{"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/media?parent=12817"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/categories?post=12817"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mcqsadda.com\/index.php\/wp-json\/wp\/v2\/tags?post=12817"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}