PH Meters Multiple Choice Questions and Answers

1. In Hydrogen electrode, the electrode is placed in a solution of ____ M Hcl. Fill in the blank.

a) 0.5

b) 1

c) 2

d) 3

Answer: 1.

2. Which of the following is the value of hydrogen ion concentration of pure water?

a) 1×10^7 moles/litre

b) 1×10^5 moles/litre

c) 1×10^6 moles/litre

d) 1×10^8 moles/litre

Answer: 1×10^7 moles/litre.

3. Which of the following is the relation between hydrogen and hydroxyl ion concentration of pure water?

a) Value of hydrogen ion concentration is greater

b) Value of hydroxyl ion concentration is greater

c) They are both always the same

d) The concentrations keep changing

Answer: They are both always the same.

4. Which of the following is not a failure in pH meters?

a) Defective electrodes

b) Defective input circuitry

c) Defective electronic circuitry

d) Defective calibration

Answer: Defective calibration.

5. The electrodes used in pH measurement have which of the following internal resistances?

a) Very low resistance

b) Moderate resistance

c) Very high resistance

d) No resistance

Answer: Very high resistance.

6. Which of the following is the simplest of pH meters?

a) Null-detector type pH meter

b) Direct reading type pH meter

c) Digital pH meter

d) Modern pH meter

Answer: Null-detector type pH meter.

7. Which of the following is not the characteristic of null-detector type pH meter?

a) It can be battery operated

b) It has less accuracy

c) It is easy to maintain

d) Its electronic circuits are simple

Answer: It has less accuracy.

8. Which of the following can be used to provide automatic temperature compensation?

a) Proper insulation

b) Calibration for different temperatures

c) Thermistor

d) Thermometer

Answer: Thermistor.

9. Which of the following is not the characteristic of chopper amplifier pH meter?

a) Direct voltage from the electrodes is chopped at the main frequency

b) Using choppers for high-input resistance gives rise to spikes of waveforms at the output

c) It leads to stability in DC output of phase-sensitive rectifier

d) Magnitude of surge increases in the glass electrode output

Answer: It leads to stability in DC output of phase-sensitive rectifier.

10. Which of the following is not the characteristic of direct reading type pH meters?

a) Simple operation

b) Quick to use

c) Continuous indication output

d) It requires balancing process

Answer: It requires balancing process.

11. In vibrating condenser amplifier type pH meter, to maintain good performance which of the following has to be done?

a) Frequency of the vibrator should be stable

b) Frequency of the vibrator should be constant

c) Amplitude of the vibrator should be constant

d) Both frequency and amplitude of the vibrator should be constant and stable

Answer: Both frequency and amplitude of the vibrator should be constant and stable.

12. In which of the following ways can the disadvantages of chopper amplifier type pH meter be overcome?

a) Using zero corrected DC amplifier

b) Using modern design

c) Using digital design

d) Using vibrating condenser

Answer: Using vibrating condenser.

13. Which of the following is not the advantage of gel-filled electrodes?

a) Low maintenance

b) Rugged in construction

c) Easy to maintain

d) Does not cause clogging

Answer: Does not cause clogging.

14. In which of the following ways can zero drift be reduced in pH meters?

a) Using filter

b) Giving zero adjustment arrangement

c) Keeping the input impedance high

d) Using balanced and differential amplifiers

Answer: Using balanced and differential amplifiers.

15. Which of the following is the formula for pH calculation?

a) log10[H+]

b) -log10[H+]

c) log2[H+]

d) -log2[H+]

Answer: -log10[H+].

16. pH meters can be considered as voltage sources with which of the following internal resistances?

a) Very low resistance

b) Moderate resistance

c) Very high resistance

d) No resistance

Answer: Very high resistance.

17. In combination electrode, which of the following electrodes are built together?

a) Primary electrode, secondary reference electrode

b) Primary reference electrode, glass electrode

c) Glass electrode, secondary reference electrode

d) Glass electrode with another glass electrode

Answer: Glass electrode, secondary reference electrode.

18. The reference electrodes in combination electrodes are protected against light using which of the following?

a) Emerald green glass

b) Ruby red glass

c) Sapphire blue glass

d) Pearl white glass

Answer: Ruby red glass.

19. Which of the following reference electrodes are used as internal and external reference electrodes in combination electrodes?

a) Silver/silver chloride electrode

b) Calomel electrode

c) Mercury/mercury sulphate electrode

d) Mercury/mercury chloride electrode

Answer: Silver/silver chloride electrode.

20. Combination electrodes containing the electrolyte in gel format have which of the following advantages over normal ones?

a) Simple to use

b) Low maintenance

c) Low cost

d) More accurate

Answer: Low maintenance.

21. In which of the following solutions must combination electrodes be soaked after cleaning?

a) KCl

b) LiCl

c) KNO3

d) K2SO4

Answer: KCl.

22. Beckman coulter gel filled combination electrodes provide which of the following features to overcome various problems that occur in gel filled electrodes?

a) Filters

b) Semi-permeable membrane

c) Gas-permeable membrane

d) Micro-pore junction

Answer: Micro-pore junction.

23. Which of the following salt bridge solutions must be used for silver/silver chloride electrode?

a) Saturated KCl

b) Saturated K2SO4

c) Saturated LiCl

d) Saturated KNO3

Answer: Saturated KCl.

24. Which of the following cannot be used as secondary reference electrode?

a) Calomel electrode

b) Silver-silver chloride electrode

c) Mercury-mercury sulphate electrode

d) Glass electrode

Answer: Glass electrode.

25. The calomel electrodes are classified based on which of the following?

a) Materials used in the electrode

b) Amount of mercury present

c) Concentration of Kcl

d) Purity of mercury

Answer: Concentration of Kcl.

26. Which of the following is known as calomel?

a) Silver chloride

b) Mercury chloride

c) Potassium chloride

d) Mercury sulphate

Answer: Mercury chloride.

27. Which of the following calomel electrodes are used for accurate work?

a) Saturated calomel electrode

b) Electrode with 0.1M Kcl

c) Electrode with 1M Kcl

d) Electrode with 2M Kcl

Answer: Electrode with 0.1M Kcl.

28. Which of the following is not the disadvantage of glass electrodes?

a) Poor readings are obtained in buffered or unbuffered solutions

b) The electrode must be washed thoroughly with distilled water to obtain proper results

c) Materials suspended on glass should be wiped out neatly to obtain proper results

d) It is affected by oxidation reduction potentials in the solution

Answer: It is affected by oxidation reduction potentials in the solution.

29. When the calomel electrode acts as the cathode which of the following does not occur?

a) Mercury ions are discharged at the electrode

b) More calomel passes into the solution

c) There is a decrease in the concentration of chloride ions

d) There is an increase in the concentration of chloride ions

Answer: There is an increase in the concentration of chloride ions.

30. Which of the following is not the characteristics of silver/silver chloride electrode?

a) These electrodes have good electrical and chemical stability

b) It can be used in temperatures greater than 600oC

c) It can be used in places or solutions that have strong reducing agents

d) It should not be used in solutions that contain proteins, sulphide or bromide

Answer: It can be used in places or solutions that have strong reducing agents.

31. Calomel electrode can behave as which of the following components?

a) Anode only

b) Cathode only

c) Anode or cathode

d) Salt bridge

Answer: Anode or cathode.

32. The gel used in combination electrodes does not have which of the following characteristic?

a) Non-toxic

b) USP grade

c) Inorganic material

d) Polyacrylamide

Answer: Inorganic material.

33. Which of the following is not the characteristics of a calomel electrode?

a) The potential of electrode is not temperature dependent

b) Preparation of electrode is easy

c) Value of potential or emf is higher for lower concentration of Kcl

d) Value of potential decreases with increasing concentration of Kcl

Answer: The potential of electrode is not temperature dependent.

34. Good choice for storing combination electrodes is in a buffer solution having which of the following pH?

a) pH1

b) pH2

c) pH3

d) pH4

Answer: pH4.

35. Which of the following is the relation between the concentration of hydrogen and hydroxyl ions in a basic solution?

a) Value of hydrogen ion concentration is greater

b) Value of hydroxyl ion concentration is greater

c) They are both always the same

d) The concentrations keep changing

Answer: Value of hydroxyl ion concentration is greater.

36. Pure water is known to be which of the following?

a) Weak electrolyte

b) Strong electrolyte

c) Neither weak nor strong

d) Not an electrolyte

Answer: Weak electrolyte.

37. Which of the following is the value of hydroxyl ion concentration of pure water?

a) 1×10^7 moles/litre

b) 1×10^5 moles/litre

c) 1×10^6 moles/litre

d) 1×10^8 moles/litre

Answer: 1×10^7 moles/litre.

38. Which of the following is the relation between the concentration of hydrogen and hydroxyl ions in an acidic solution?

a) Value of hydrogen ion concentration is greater

b) Value of hydroxyl ion concentration is greater

c) They are both always the same

d) The concentrations keep changing

Answer: Value of hydrogen ion concentration is greater.

39. The Nernst equation is given by which of the following statements?

a) E=Eo + 2.303 RT/F log CH

b) E=Eo – 2.303 RT/F log CH

c) E=Eo + 2.303 RT×F log CH

d) E=Eo – 2.303 RT×F log CH

Answer: E=Eo + 2.303 RT/F log CH.

40. Why is Standard hydrogen electrode called as the primary reference electrode?

a) It has a known output potential

b) It has a constant output potential

c) Its output potential is independent of the composition of the solution

d) Its output potential is zero volts

Answer: Its output potential is zero volts.

41. Which of the following is not the characteristic of a reference electrode?

a) It must have a known output potential

b) It must have a constant output potential

c) Its output potential is dependent on the composition of the solution

d) It is employed in conjunction with the indicator or working electrode

Answer: Its output potential is dependent on the composition of the solution.

42. Which of the following is not the disadvantage of hydrogen electrode?

a) Platinum can be easily poisoned

b) Presence of oxidising agents alters the potential

c) It gives a salt error

d) H2 gas at 1 atmospheric pressure is difficult to set up and transport

Answer: It gives a salt error.

43. Which of the following is the simple and most convenient hydrogen electrode?

a) Pascal Hydrogen electrode

b) Bourne Hydrogen electrode

c) Hilderbant Hydrogen electrode

d) West Hydrogen electrode

Answer: Hilderbant Hydrogen electrode.

44. Which of the following cannot form the inner reference electrode in glass electrodes?

a) Silver electrode

b) Copper electrode

c) Calomel electrode

d) Silver chloride electrode

Answer: Copper electrode.

45. The composition of glass membrane in glass electrode cannot have which of the following?

a) Sodium silicate

b) Calcium silicate

c) Lithium silicate

d) Barium silicate

Answer: Barium silicate.

46. Hydrogen electrode which is the reference electrode can be used as which of the following?

a) Anode only

b) Cathode only

c) Anode or Cathode

d) Salt bridge

Answer: Anode or Cathode.

47. Which of the following is the purpose of added membranes in the glass membrane of the glass electrode?

a) They act as tightners

b) They act as filters

c) They act as conditioners

d) They act as collectors

Answer: They act as tightners.

48. Which of the following is not the advantage of glass electrodes?

a) It gives accurate results for high as well as low pH values

b) It is simple to operate

c) It has no salt error

d) Modern electrodes can withstand severe treatment

Answer: It gives accurate results for high as well as low pH values.

49. The pH response of glass electrode is limited entirely to the area of the special glass membrane bulb.

a) True

b) False

Answer: True.

50. If hydrogen electrode acts as cathode, hydrogen is reduced.

a) True

b) False

Answer: True.

51. The measurement of hydrogen ion concentration can be made by measuring the potential developed in an electrochemical cell.

a) True

b) False

Answer: True.

52. Slope factor is independent of temperature.

a) True

b) False

Answer: False

53. While using reference electrodes, the internal liquid level should always be kept above that of the sample solution.

a) True

b) False

Answer: True.

54. LiCl salt bridge is more suitable in organic solvents than KCl.

a) True

b) False

Answer: True.

55. In combination electrodes, both the electrodes must be maintained at different temperatures.

a) True

b) False

Answer: False

56. Gel filled combination electrodes operate in a wide temperature range.

a) True

b) False

Answer: True.

57. Calomel electrode can behave as Anode or cathode components.

a) True

b) False

Answer: True.

58. -log10[H+] is the formula for pH calculation?

a) True

b) False

Answer: True.

59. If an instrument fails to balance at zero, it is most likely that the electrodes are defective.

a) True

b) False

Answer: False

60. The zero stability of vibrating condenser amplifier type pH meter is much better than a direct coupled amplifier.

a) True

b) False

Answer: True.