Introduction: Understanding the concepts of accuracy, precision and significant figures is essential for B.Pharm students performing pharmaceutical analysis and laboratory measurements. Accurate measurements reflect closeness to true value, while precise results show repeatability; both affect assay validity, quality control and formulation development. Mastery of significant figures and rounding rules prevents propagation of error in calculations for concentration, dosage and titration. This topic covers measurement uncertainty, systematic and random errors, percent error, standard deviation basics and practical rules for reporting results in pharmaceutical labs. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What best defines accuracy in pharmaceutical measurements?
- Closeness of repeated measurements to each other
- Closeness of a measurement to the true or accepted value
- The number of significant figures in the measurement
- The precision of the measuring instrument
Correct Answer: Closeness of a measurement to the true or accepted value
Q2. What best defines precision in the laboratory context?
- Closeness of a measurement to the true value
- Reproducibility or repeatability of measurements
- Number of decimal places reported
- Difference between measured and accepted value
Correct Answer: Reproducibility or repeatability of measurements
Q3. Which type of error is most often associated with instrument calibration problems?
- Random error
- Systematic error
- Human transcription error
- Sampling error
Correct Answer: Systematic error
Q4. Which rule applies when multiplying or dividing values concerning significant figures?
- Result should have the same number of decimal places as the least precise addend
- Result should have the same number of significant figures as the value with the fewest significant figures
- Round the result to two decimal places always
- Use the average number of significant figures from all operands
Correct Answer: Result should have the same number of significant figures as the value with the fewest significant figures
Q5. Which rule applies when adding or subtracting values about significant figures?
- Match decimal places to the least number of decimal places among operands
- Match significant figures to the smallest number among operands
- Round to one significant figure always
- Do not round until final result but keep original significant figures
Correct Answer: Match decimal places to the least number of decimal places among operands
Q6. How many significant figures are in 0.00450 g?
- 2
- 3
- 4
- 1
Correct Answer: 3
Q7. How many significant figures are in 1200 (ambiguous, no decimal shown)?
- 2
- 3
- 4
- Ambiguous; cannot determine without more context
Correct Answer: Ambiguous; cannot determine without more context
Q8. Which zeros are never significant?
- Trailing zeros in a decimal number
- Leading zeros before the first nonzero digit
- Zeros between nonzero digits
- All zeros are sometimes significant
Correct Answer: Leading zeros before the first nonzero digit
Q9. In pharmacology, percent error is most useful to assess what?
- Precision of pipettes
- Magnitude of systematic deviation from a reference value
- Number of significant figures in a measurement
- Instrument resolution
Correct Answer: Magnitude of systematic deviation from a reference value
Q10. If three replicate assay values are 10.2, 10.4 and 10.3 mg, what describes the data?
- High accuracy, low precision
- Low accuracy, high precision
- High precision, likely high accuracy if close to true value
- Unreliable because values differ
Correct Answer: High precision, likely high accuracy if close to true value
Q11. What is the standard deviation a measure of?
- Systematic error in measurements
- Spread or dispersion of data around the mean
- Difference between two measurements
- Instrument calibration factor
Correct Answer: Spread or dispersion of data around the mean
Q12. Which statement about significant figures and exact numbers is correct?
- Exact counted numbers have infinite significant figures
- Exact numbers have no significant figures
- Exact numbers limit the significant figures of results
- Exact numbers must be rounded to three significant figures
Correct Answer: Exact counted numbers have infinite significant figures
Q13. When reporting concentration from a calibrated instrument, why include uncertainty?
- Uncertainty is optional and rarely useful
- It quantifies measurement reliability and helps regulatory decisions
- It makes the value look less precise
- It is required only in research not in quality control
Correct Answer: It quantifies measurement reliability and helps regulatory decisions
Q14. How many significant figures should the product of 2.50 and 3.1 have?
- Two significant figures
- Three significant figures
- One significant figure
- Four significant figures
Correct Answer: Two significant figures
Q15. For addition: 12.11 + 0.3 + 1.234 = ? with correct sig-fig handling
- 13.644
- 13.6
- 13.64
- 13.7
Correct Answer: 13.6
Q16. Which practice improves precision in volumetric pipetting?
- Using different pipettes each time
- Pre-rinsing the pipette tip with the solution and using consistent technique
- Reading the meniscus from different angles
- Shaking the pipette vigorously after filling
Correct Answer: Pre-rinsing the pipette tip with the solution and using consistent technique
Q17. What does a low standard error of the mean indicate?
- Large variability between individual measurements
- The sample mean estimates the population mean precisely
- Systematic bias in measurement
- Insufficient sample size
Correct Answer: The sample mean estimates the population mean precisely
Q18. Which scenario indicates high accuracy but low precision?
- Measurements clustered tightly around the true value
- Measurements widely scattered but centered near the true value
- Measurements clustered away from the true value
- Consistent instrument drift toward higher values
Correct Answer: Measurements widely scattered but centered near the true value
Q19. When reporting pH measured as 7.234 with instrument uncertainty ±0.02, how should you report significant figures?
- Report as 7.234 ± 0.02
- Report as 7.23 ± 0.02
- Report as 7 ± 0.02
- Report as 7.2340 ± 0.02
Correct Answer: Report as 7.23 ± 0.02
Q20. Which of the following best describes random error?
- Error that consistently shifts measurements in one direction
- Unpredictable variations that affect measurement precision
- Error due to an incorrectly labeled reagent
- Operator bias introduced intentionally
Correct Answer: Unpredictable variations that affect measurement precision
Q21. A balance reads 1.234 g with readability 0.001 g. What is the implied number of significant figures?
- Four significant figures
- Three significant figures
- Two significant figures
- Infinite significant figures
Correct Answer: Four significant figures
Q22. In propagation of error for independent variables, combined relative error for multiplication is approximated by?
- Sum of absolute errors
- Square root of sum of squared relative errors
- Product of the relative errors
- Difference of relative errors
Correct Answer: Square root of sum of squared relative errors
Q23. Which is the correct way to round 2.345 when keeping three significant figures?
- 2.34
- 2.35
- 2.345
- 2.3
Correct Answer: 2.35
Q24. When reporting drug assay results, why avoid reporting excessive significant figures?
- It always improves regulatory acceptance
- Excess figures imply unjustified precision and can mislead interpretation
- Fewer figures reduce workload for analysts
- More figures always increase accuracy
Correct Answer: Excess figures imply unjustified precision and can mislead interpretation
Q25. Which measurement would be least precise based on instrument resolution?
- Mass measured to 0.0001 g
- Volume measured with a burette to 0.05 mL
- Length measured with a ruler marked in mm
- Temperature measured with a thermometer reading to 0.1°C
Correct Answer: Length measured with a ruler marked in mm
Q26. How should trailing zeros in a number like 2.300 be interpreted in significant figures?
- Only two significant figures
- Two or three significant figures depending on context
- Four significant figures because zeros after decimal are significant
- No significant figures
Correct Answer: Four significant figures because zeros after decimal are significant
Q27. If measured concentrations are biased high due to reagent impurity, which improvement addresses accuracy?
- Use the same contaminated reagent for all measurements
- Replace reagent with a certified reference material or purer reagent and recalibrate
- Increase number of replicates only
- Report more decimal places
Correct Answer: Replace reagent with a certified reference material or purer reagent and recalibrate
Q28. Which concept explains why averaging several measurements can improve the estimate of the true value?
- Averaging increases systematic error
- Central limit effect reduces influence of random errors on the mean
- Averaging increases number of significant figures
- Averaging hides poor technique
Correct Answer: Central limit effect reduces influence of random errors on the mean
Q29. For a titration end point read as 24.60 mL on a burette with 0.05 mL markings, how many decimal places should be reported?
- Two decimal places (24.60 mL)
- One decimal place (24.6 mL)
- Three decimal places (24.600 mL)
- None, report as 25 mL
Correct Answer: Two decimal places (24.60 mL)
Q30. Which practice reduces random error in weighing a sample for formulation?
- Using poor quality weigh boats
- Minimizing drafts and using a draft shield with consistent technique
- Weighing sporadically without standard procedure
- Ignoring balance warm-up time
Correct Answer: Minimizing drafts and using a draft shield with consistent technique
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com