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Process Analyser Quiz

Test yourself with 20 multiple choice questions. Check your answers to get a score and an explanation for every question.

20 questionsInstant scoreExplanationsInterview practice

Process Analyser Quiz: 20 Questions

Choose one answer for each question, then press Check answers. Explanations appear after checking.

1. A pH of 3 means hydrogen ion concentration of about:

Answer: 10⁻³ mol/L. pH = −log₁₀[H+]. Learn more: pH

2. Theoretical pH electrode slope at 25 °C is:

Answer: 59.16 mV/pH. Nernst slope 0.1984 × T. Learn more: Nernst Slope

3. A pH electrode at pH 7 ideally gives:

Answer: About 0 mV. The isopotential point is near pH 7. Learn more: Nernst Slope

4. pH calibration normally uses:

Answer: pH 7 and a buffer near process pH. Two point calibration sets offset and slope. Learn more: Buffer Solution

5. Which buffer absorbs CO₂ and drifts fastest?

Answer: pH 10. Alkaline buffers react with CO₂ from air. Learn more: Buffer Solution
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6. pH temperature compensation corrects:

Answer: The electrode slope. Not the real change of sample pH with temperature. Learn more: pH Temperature Compensation

7. Conductivity equals conductance multiplied by:

Answer: The cell constant. κ = G × K. Learn more: Cell Constant

8. Typical conductivity temperature coefficient is about:

Answer: 2 % per °C. Readings are referenced to 25 °C. Learn more: Conductivity Temperature Compensation

9. 1000 µS/cm with factor 0.65 gives TDS of:

Answer: 650 mg/L. TDS ≈ k × κ. Learn more: Total Dissolved Solids

10. Ultrapure water conductivity at 25 °C is about:

Answer: 0.055 µS/cm. Set by water self ionisation. Learn more: Conductivity
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11. Dissolved oxygen saturation in fresh water at 20 °C is about:

Answer: 9.1 mg/L. It falls with temperature and salinity. Learn more: Dissolved Oxygen

12. Turbidity per ISO 7027 is reported in:

Answer: FNU. Infrared light at 90°; NTU with white light. Learn more: Turbidity

13. ORP is measured with:

Answer: A platinum or gold electrode and a reference. Reported in mV. Learn more: Oxidation Reduction Potential

14. 50 ppm CO (M 28.01) at 25 °C is about:

Answer: 57 mg/m³. 50 × 28.01 ÷ 24.45. Learn more: ppm to mg/m³ Conversion

15. Zirconia oxygen probes operate at about:

Answer: 600 °C or more. Zirconia conducts oxygen ions only when hot. Learn more: Zirconia Oxygen Sensor
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16. 3 % O₂ in flue gas means excess air of about:

Answer: 17 %. O₂ ÷ (20.9 − O₂) × 100. Learn more: Excess Air

17. Emission results are corrected to a reference O₂ to:

Answer: Prevent dilution with air hiding emissions. C_ref = C × (20.9 − O₂ref) ÷ (20.9 − O₂meas). Learn more: Emission Oxygen Correction

18. NDIR analysers cannot measure:

Answer: Oxygen. Oxygen does not absorb infrared. Learn more: NDIR Gas Analyser

19. Sample lag time equals:

Answer: Line volume ÷ sample flow. Fast loops reduce it. Learn more: Sample Lag Time

20. Water hardness is commonly expressed as:

Answer: mg/L as CaCO₃. 2.497 Ca + 4.118 Mg. Learn more: Water Hardness
0 of 20 answered
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About this Quiz

20 multiple choice questions on process analyser, the kind asked in instrumentation interviews, technician exams and plant training. Each answer comes with a short explanation, so the quiz works as a revision sheet too.

Show answer key
  1. 10⁻³ mol/L: pH = −log₁₀[H+]. Learn more: pH
  2. 59.16 mV/pH: Nernst slope 0.1984 × T. Learn more: Nernst Slope
  3. About 0 mV: The isopotential point is near pH 7. Learn more: Nernst Slope
  4. pH 7 and a buffer near process pH: Two point calibration sets offset and slope. Learn more: Buffer Solution
  5. pH 10: Alkaline buffers react with CO₂ from air. Learn more: Buffer Solution
  6. The electrode slope: Not the real change of sample pH with temperature. Learn more: pH Temperature Compensation
  7. The cell constant: κ = G × K. Learn more: Cell Constant
  8. 2 % per °C: Readings are referenced to 25 °C. Learn more: Conductivity Temperature Compensation
  9. 650 mg/L: TDS ≈ k × κ. Learn more: Total Dissolved Solids
  10. 0.055 µS/cm: Set by water self ionisation. Learn more: Conductivity
  11. 9.1 mg/L: It falls with temperature and salinity. Learn more: Dissolved Oxygen
  12. FNU: Infrared light at 90°; NTU with white light. Learn more: Turbidity
  13. A platinum or gold electrode and a reference: Reported in mV. Learn more: Oxidation Reduction Potential
  14. 57 mg/m³: 50 × 28.01 ÷ 24.45. Learn more: ppm to mg/m³ Conversion
  15. 600 °C or more: Zirconia conducts oxygen ions only when hot. Learn more: Zirconia Oxygen Sensor
  16. 17 %: O₂ ÷ (20.9 − O₂) × 100. Learn more: Excess Air
  17. Prevent dilution with air hiding emissions: C_ref = C × (20.9 − O₂ref) ÷ (20.9 − O₂meas). Learn more: Emission Oxygen Correction
  18. Oxygen: Oxygen does not absorb infrared. Learn more: NDIR Gas Analyser
  19. Line volume ÷ sample flow: Fast loops reduce it. Learn more: Sample Lag Time
  20. mg/L as CaCO₃: 2.497 Ca + 4.118 Mg. Learn more: Water Hardness
Tip: take the quiz before an interview, note the questions you missed and read the linked article for those topics.
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Frequently Asked Questions

Is this quiz free?

Yes. No sign up is needed and you can retake it as often as you like.

Are the answers explained?

Yes. After you check your answers, each question shows the correct answer and a short explanation.

Where can I find more questions?

See the Interview Q&A section of instrumentationblog.in and the linked article below.

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