Calibration of electronic balance MCQs With Answer

Calibration of electronic balance MCQs With Answer

Accurate weighing is critical in pharmaceutical practice; calibration of electronic balance ensures reliability, traceability, and compliance. This introduction reviews principles of electronic balance calibration, including concepts of accuracy, precision, linearity, sensitivity, readability, and minimum weight. It outlines calibration procedures using standard weights, routine checks, environmental controls, documentation, and acceptance criteria within GMP and B.Pharm laboratory settings. Emphasis is on practical steps: warm-up, level adjustment, internal/external calibration, use of calibration certificates, and corrective actions when out of tolerance. Understanding these topics prepares students for quality control, validation (IQ/OQ/PQ), and everyday pharmaceutical weighing. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary purpose of calibrating an electronic balance in a pharmaceutical lab?

• To change the balance display language
• To ensure weighing results are accurate, precise, and traceable
• To increase the maximum capacity of the balance
• To clean the weighing pan

Correct Answer: To ensure weighing results are accurate, precise, and traceable

Q2. Which standard weight class is typically recommended for routine calibration checks in a B.Pharm laboratory?

• Class M1
• Class F2
• Class E2
• Class M3

Correct Answer: Class E2

Q3. What does the term ‘readability’ of an electronic balance refer to?

• The maximum load the balance can hold
• The smallest difference in mass that the balance can display
• The physical size of the weighing pan
• The time the balance takes to warm up

Correct Answer: The smallest difference in mass that the balance can display

Q4. Minimum weight is important because below this weight the balance:

• Becomes more accurate
• May not meet required accuracy due to variability and uncertainty
• Will automatically self-calibrate
• Consumes more power

Correct Answer: May not meet required accuracy due to variability and uncertainty

Q5. Which environmental factor has the greatest immediate effect on balance performance?

• Ambient light intensity
• Air currents and drafts
• Paint color of the walls
• Time of day

Correct Answer: Air currents and drafts

Q6. What is the recommended practice before performing calibration on an electronic balance?

• Move the balance to a different room
• Warm-up the balance for manufacturer-recommended time and level it
• Run solvents across the pan
• Turn off the balance for 24 hours

Correct Answer: Warm-up the balance for manufacturer-recommended time and level it

Q7. Internal calibration differs from external calibration in that internal calibration:

• Requires certified external weights
• Is performed using an internal reference mass built into the balance
• Is more accurate than any external method
• Does not need documentation

Correct Answer: Is performed using an internal reference mass built into the balance

Q8. Which parameter assesses the balance’s ability to produce the same result under identical conditions?

• Linearity
• Repeatability
• Sensitivity
• Capacity

Correct Answer: Repeatability

Q9. Linearity testing of a balance evaluates:

• Whether zero is displayed correctly
• Deviation of readings across the full weighing range from a straight-line response
• How fast the display updates
• Electrical wiring quality

Correct Answer: Deviation of readings across the full weighing range from a straight-line response

Q10. Traceability of calibration means:

• Documentation links measurements to national or international standards
• The balance is labeled with the vendor name
• Weights are stored in a traceable container
• The balance has a serial number

Correct Answer: Documentation links measurements to national or international standards

Q11. Which document usually defines acceptance criteria and frequency for balance calibration in a pharmaceutical lab?

• Personal email
• Draft SOP or Standard Operating Procedure
• Random notebook entry
• Balance packaging manual

Correct Answer: Draft SOP or Standard Operating Procedure

Q12. What is the correct immediate action if a balance fails calibration and shows bias?

• Ignore and continue using it
• Document the failure, remove from use, and investigate corrective actions
• Throw away the balance
• Increase the sample size to compensate

Correct Answer: Document the failure, remove from use, and investigate corrective actions

Q13. Eccentricity test checks:

• Effect of placing a mass at different positions on the pan
• Electrical noise in the lab
• Humidity variations
• Battery life of the balance

Correct Answer: Effect of placing a mass at different positions on the pan

Q14. A balance specification lists repeatability as 0.1 mg (SD). Which practice helps verify this?

• Weighing a heavy item once
• Performing multiple weighings of the same certified weight and calculating standard deviation
• Turning off the balance between measurements
• Using different weights each time

Correct Answer: Performing multiple weighings of the same certified weight and calculating standard deviation

Q15. Which calibration certificate detail is essential for traceability?

• Color of the certificate paper
• Name of the technician only
• Reference to the national standard and uncertainty of the standard weights
• Balance model only

Correct Answer: Reference to the national standard and uncertainty of the standard weights

Q16. What does ‘sensitivity’ of a balance mean?

• Maximum capacity of the balance
• Change in displayed value per unit change in mass
• Time required to perform calibration
• Stability over months

Correct Answer: Change in displayed value per unit change in mass

Q17. Which practice reduces electrostatic effects during weighing of powders?

• Wearing wool gloves
• Using anti-static devices, ionizers, or grounded tweezers and proper sample containers
• Weighing in direct sunlight
• Placing samples near a fan

Correct Answer: Using anti-static devices, ionizers, or grounded tweezers and proper sample containers

Q18. In a balance calibration log, which entry is NOT appropriate?

• Date and time of calibration
• Results, technician name, and acceptance status
• Corrective actions taken if failed
• Technician’s personal phone number unrelated to work

Correct Answer: Technician’s personal phone number unrelated to work

Q19. Which is the best weight to use for a quick daily performance check of a 200 g balance?

• A 0.01 g weight
• A certified weight near 100 g or 50% of full scale as recommended
• A random coin
• No weight—just power cycling

Correct Answer: A certified weight near 100 g or 50% of full scale as recommended

Q20. Uncertainty in balance calibration refers to:

• The exact true error without range
• Quantified doubt about the measurement including contributions from standards and procedure
• The age of the balance
• Noise in the lab music

Correct Answer: Quantified doubt about the measurement including contributions from standards and procedure

Q21. Which of the following indicates a need for re-calibration?

• Balance produces identical results repeatedly
• Calibration drift observed or out-of-tolerance results after transportation or repair
• Balance is located in the controlled lab environment
• Manufacturer warranty active

Correct Answer: Calibration drift observed or out-of-tolerance results after transportation or repair

Q22. Which validation stage formally documents that the balance has been installed correctly?

• Operational Qualification (OQ)
• Performance Qualification (PQ)
• Installation Qualification (IQ)
• Calibration Qualification (CQ)

Correct Answer: Installation Qualification (IQ)

Q23. What is the role of temperature in balance calibration and use?

• Temperature has no effect
• Temperature affects buoyancy and electronic stability; calibration should account for nominal lab temperature and equilibration
• Only affects the display color
• Higher temperature increases readability always

Correct Answer: Temperature affects buoyancy and electronic stability; calibration should account for nominal lab temperature and equilibration

Q24. Which statement about tare and zero functions is correct?

• Tare stores a weight permanently
• Zero sets the displayed value to zero with or without a container present; tare subtracts container weight so sample mass displays
• They perform the same action
• Zero is used only during calibration

Correct Answer: Zero sets the displayed value to zero with or without a container present; tare subtracts container weight so sample mass displays

Q25. What is the effect of not leveling a balance before calibration?

• No impact on results
• It can cause systematic errors and failed calibration
• Only affects the pan appearance
• Improves sensitivity

Correct Answer: It can cause systematic errors and failed calibration

Q26. When selecting calibration weights, one should consider:

• Color matching with the balance
• Appropriate class, mass values, and calibration traceability
• Whether they fit in your pocket
• Number of certifications the manufacturer has

Correct Answer: Appropriate class, mass values, and calibration traceability

Q27. Which test assesses short-term stability of a balance at a single mass?

• Linearity test
• Repeatability or stability test using multiple readings of the same mass over short interval
• Capacity test
• Temperature ramp test

Correct Answer: Repeatability or stability test using multiple readings of the same mass over short interval

Q28. How should certified weights be handled to maintain accuracy?

• Touch them with bare hands frequently
• Handle with clean gloves or tweezers, store in protective case, and avoid contamination
• Clean with solvents daily
• Store them on the balance pan permanently

Correct Answer: Handle with clean gloves or tweezers, store in protective case, and avoid contamination

Q29. Which is a common acceptance criterion for balance calibration in pharmaceutical labs?

• Any reading is acceptable if it looks reasonable
• Deviation must be within manufacturer or SOP specified limits, often related to readability and percent of test mass
• Only visual inspection is required
• Acceptance only depends on technician’s opinion

Correct Answer: Deviation must be within manufacturer or SOP specified limits, often related to readability and percent of test mass

Q30. What is the difference between verification and calibration of a balance?

• Verification is informal; calibration is illegal
• Verification checks performance against criteria; calibration adjusts or documents instrument performance against standards
• There is no difference
• Calibration only cleans the balance

Correct Answer: Verification checks performance against criteria; calibration adjusts or documents instrument performance against standards

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