Sieve and sieve analysis are fundamental techniques in pharmaceutical powder characterization, crucial for B.Pharm students studying particle size distribution, mesh size, and granulometry. Proper sieve selection, understanding aperture versus mesh number, and following USP and pharmacopoeial methods ensure accurate particle size analysis for tablets, capsules, granules and suspensions. Sieve testing (wet and dry), sieve shaker operation, sample preparation, and calculation of percent finer, D10/D50/D90 and span affect drug dissolution, content uniformity and flow properties. Mastery of sieve calibration, standard sieves, Tyler/metric conversions, and common errors improves formulation development and quality control. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the main objective of sieve analysis in pharmaceutical powder characterization?
- To determine moisture content
- To measure particle size distribution
- To estimate bulk density
- To assess chemical purity
Correct Answer: To measure particle size distribution
Q2. Which of the following is a standard used for sieve specifications in pharmaceutics?
- ISO 9001
- USP (United States Pharmacopeia)
- FDA GLP Manual
- ICH Q7
Correct Answer: USP (United States Pharmacopeia)
Q3. What does the sieve mesh number indicate?
- Number of openings per linear inch
- Weight of the sieve in grams
- Thickness of the wire in micrometers
- Percentage retained
Correct Answer: Number of openings per linear inch
Q4. Which sieve series is commonly referenced in pharmaceutical sieve analysis?
- Tyler sieve series
- SIRO series
- Graham sieve series
- Keller series
Correct Answer: Tyler sieve series
Q5. What is the difference between aperture size and mesh number?
- Aperture size is area, mesh number is weight
- Aperture size is the opening dimension, mesh number is openings per inch
- They are identical terms
- Mesh number measures thickness, aperture size measures diameter
Correct Answer: Aperture size is the opening dimension, mesh number is openings per inch
Q6. Which method is preferred for very fine particles that tend to clog sieve openings?
- Dry sieve only
- Wet sieving
- Manual shaking only
- Visual inspection
Correct Answer: Wet sieving
Q7. What effect does particle size distribution have on tablet dissolution?
- No effect
- Smaller particles generally increase dissolution rate
- Only chemical composition affects dissolution
- Larger particles always increase dissolution rate
Correct Answer: Smaller particles generally increase dissolution rate
Q8. Which parameter from sieve analysis represents the particle diameter below which 50% of the sample lies?
- D10
- D50
- D90
- Span
Correct Answer: D50
Q9. How is percent finer (percent passing) usually calculated?
- (Cumulative mass retained / total mass) × 100
- (Mass passing a sieve / total mass) × 100
- Weight of sieve / sample weight × 100
- Mesh number / aperture size × 100
Correct Answer: (Mass passing a sieve / total mass) × 100
Q10. Which instrument commonly automates the sieving process in labs?
- Rotary evaporator
- Size-exclusion chromatograph
- Sieve shaker (mechanical shaker)
- Hot plate
Correct Answer: Sieve shaker (mechanical shaker)
Q11. What is the purpose of stacking sieves from largest to smallest aperture during analysis?
- To save space on the bench
- To separate particles progressively by size
- To increase sample moisture
- To reduce sample weight
Correct Answer: To separate particles progressively by size
Q12. Which of the following is a common error in sieve analysis?
- Using calibrated sieves
- Overloading the top sieve with too much sample
- Arranging sieves from coarse to fine
- Cleaning sieves between runs
Correct Answer: Overloading the top sieve with too much sample
Q13. What does D90 indicate in sieve analysis?
- Diameter below which 90% of particles lie
- Diameter above which 90% of particles lie
- Average particle diameter
- Standard deviation of particle sizes
Correct Answer: Diameter below which 90% of particles lie
Q14. Which calculation gives a measure of distribution width: span, standard deviation, or mean?
- Mean only
- Span
- None of these
- Median
Correct Answer: Span
Q15. How is span defined in particle size analysis?
- (D90 − D10) / D50
- D50 − D10
- D90 × D10 / D50
- D10 / D90
Correct Answer: (D90 − D10) / D50
Q16. Why is sample splitting important before sieve analysis?
- To change particle shape
- To obtain a representative smaller sample
- To increase moisture content
- To sterilize the sample
Correct Answer: To obtain a representative smaller sample
Q17. Which device is commonly used to divide a bulk powder into representative portions?
- Funnel and beaker
- Rotary sample divider
- Mortar and pestle
- Hot air oven
Correct Answer: Rotary sample divider
Q18. What is the effect of moisture on sieve analysis of cohesive powders?
- Reduces bridging and improves separation
- Can cause aggregation and clogging of sieve openings
- Has no effect
- Makes particles lighter
Correct Answer: Can cause aggregation and clogging of sieve openings
Q19. Which sieving technique is suitable for hygroscopic powders prone to agglomeration?
- Dry sieving with excessive load
- Wet sieving or dispersing with a solvent
- Heating before sieving
- Using only the largest sieve
Correct Answer: Wet sieving or dispersing with a solvent
Q20. What is the recommended action if fines adhere to sieve cloth due to electrostatic charge?
- Ignore and continue
- Use antistatic measures or gentle brushing/sonication
- Increase sample size
- Use coarser sieves only
Correct Answer: Use antistatic measures or gentle brushing/sonication
Q21. Which mesh size (approximate) corresponds to a 1 mm aperture?
- 400 mesh
- 18 mesh
- 100 mesh
- 10 mesh
Correct Answer: 18 mesh
Q22. What is the nominal aperture size of a 60 mesh sieve (approx.)?
- 250 µm
- 2500 µm
- 250 nm
- 25 mm
Correct Answer: 250 µm
Q23. Which factor does NOT directly influence sieve performance?
- Shaker amplitude and time
- Sample humidity
- Color of the sieve frame
- Sample loading amount
Correct Answer: Color of the sieve frame
Q24. How is cumulative percent retained used in sieve analysis?
- To calculate bulk density
- To plot percent finer vs. sieve aperture or mesh
- To determine moisture uptake
- To measure chemical impurities
Correct Answer: To plot percent finer vs. sieve aperture or mesh
Q25. What is the purpose of using a nest of stacked sieves?
- To simultaneously separate multiple size fractions
- To increase the sample temperature
- To chemically treat the powder
- To reduce the number of sieves needed
Correct Answer: To simultaneously separate multiple size fractions
Q26. Which sieve material is commonly used for pharmaceutical sieves?
- Stainless steel woven wire
- Glass wool
- Wooden mesh
- Cotton cloth
Correct Answer: Stainless steel woven wire
Q27. For reporting particle size, which unit is most commonly used?
- Milligrams
- Micrometers (µm)
- Ohms
- Lumens
Correct Answer: Micrometers (µm)
Q28. What is an advantage of wet sieving over dry sieving?
- Faster for coarse particles only
- Reduces electrostatic and cohesive interactions for fine particles
- Makes sieving unnecessary
- Always gives larger particle sizes
Correct Answer: Reduces electrostatic and cohesive interactions for fine particles
Q29. Which of the following is a non-sieving technique for particle size analysis often used alongside sieve analysis?
- Laser diffraction
- Rotary evaporation
- Thermogravimetry
- pH titration
Correct Answer: Laser diffraction
Q30. How frequently should standard sieves be calibrated or inspected?
- Never
- Periodically as per lab SOP or regulatory guidelines
- Only once after purchase
- Every minute during use
Correct Answer: Periodically as per lab SOP or regulatory guidelines
Q31. What does the term “effective aperture” refer to?
- Nominal mesh number only
- Actual open area or dimension of sieve openings affecting sieving
- Weight capacity of the sieve
- Thickness of the frame
Correct Answer: Actual open area or dimension of sieve openings affecting sieving
Q32. Which preparation step is essential before sieving wet samples?
- Allow complete drying at room temperature only
- Disperse sample in a suitable liquid and ensure proper rinsing of sieve
- Heat to 200°C
- Freeze immediately
Correct Answer: Disperse sample in a suitable liquid and ensure proper rinsing of sieve
Q33. Which parameter would indicate a very broad particle size distribution?
- Low span value
- High span value
- D50 equals D10
- Zero percent retained on all sieves
Correct Answer: High span value
Q34. Which cleaning method is NOT recommended for delicate sieve cloths?
- Ultrasonic cleaning with compatible solvent
- Gentle brushing with soft brush
- Aggressive wire brushing or scraping
- Compressed air at low pressure
Correct Answer: Aggressive wire brushing or scraping
Q35. What does a steep slope in a cumulative percent finer vs. particle size plot indicate?
- Narrow particle size distribution
- Very broad distribution
- High moisture content
- Incorrect sample mass
Correct Answer: Narrow particle size distribution
Q36. When performing sieve analysis, why is it important to record sieve aperture designations (e.g., mesh and mm)?
- To improve aesthetics of report
- To allow reproducibility and comparison across labs
- It is not important
- To reduce sample mass
Correct Answer: To allow reproducibility and comparison across labs
Q37. Which of the following best describes air-jet sieving?
- Use of vibrating plate only
- Fluidization of powder with air to classify fine particles
- Manual hand-sifting
- Centrifugation of particles
Correct Answer: Fluidization of powder with air to classify fine particles
Q38. Which factor should be minimized to reduce human error in manual sieving?
- Use of automated sieving equipment and standardized procedures
- Use of different sieve stacks each run
- Varying shaker time randomly
- Ignoring standard operating procedures
Correct Answer: Use of automated sieving equipment and standardized procedures
Q39. Which metric is most useful when formulating to reduce segregation of a powder blend?
- Color of particles
- Particle size distribution and density matching
- pH of the powder
- Electrical conductivity
Correct Answer: Particle size distribution and density matching
Q40. What is the impact of coarse particles on powder flow?
- Always decrease flowability
- Can improve flowability compared to very fine cohesive powders
- Convert powder to liquid
- No impact at all
Correct Answer: Can improve flowability compared to very fine cohesive powders
Q41. Which chemico-physical property is directly assessed by sieve analysis?
- Particle shape only
- Particle size distribution
- Chemical potency
- Polymorphic form
Correct Answer: Particle size distribution
Q42. What is the typical next step after completing sieving and weighing retained fractions?
- Plot cumulative percent retained or percent finer vs. sieve aperture
- Discard the data
- Burn the sample
- Mix the fractions randomly
Correct Answer: Plot cumulative percent retained or percent finer vs. sieve aperture
Q43. Which statement about mesh conversion charts is true?
- Mesh number directly gives particle diameter in mm always
- Conversion charts help approximate aperture size (mm or µm) from mesh number
- They are irrelevant for sieve analysis
- They convert weight to particle size
Correct Answer: Conversion charts help approximate aperture size (mm or µm) from mesh number
Q44. Why might a pharmacopeial method specify a particular sieve shaker amplitude and time?
- To ensure consistent and reproducible sieving conditions
- To make runs longer for no reason
- To reduce sample representativeness
- To increase humidity
Correct Answer: To ensure consistent and reproducible sieving conditions
Q45. Which of the following is an indicator of sieve wear or damage?
- Uniform aperture dimensions on inspection
- Torn or elongated mesh openings and inconsistent retention
- Shiny frame only
- Proper label attached
Correct Answer: Torn or elongated mesh openings and inconsistent retention
Q46. What is the effect of long sieving time on particle breakage-sensitive materials?
- No effect
- May cause attrition and change particle size distribution
- Always improves chemical stability
- Decreases moisture content only
Correct Answer: May cause attrition and change particle size distribution
Q47. Which calculation is used to find geometric mean diameter from sieve data?
- Average of D10 and D90
- Square root of (D10 × D90)
- Sum of all diameters
- None of the above
Correct Answer: Square root of (D10 × D90)
Q48. Which aspect of dosage form performance can be directly affected by particle size distribution obtained from sieve analysis?
- Packaging color
- Dissolution rate and content uniformity
- Tablet branding
- Regulatory dossier length
Correct Answer: Dissolution rate and content uniformity
Q49. What is a common corrective step if excessive material is retained on the top sieve due to agglomerates?
- Force particles through with a spatula
- Gently break agglomerates (e.g., mild dispersion, sonication) before sieving
- Ignore and report results as-is
- Use smaller sample mass without dispersion
Correct Answer: Gently break agglomerates (e.g., mild dispersion, sonication) before sieving
Q50. Which documentation is essential after performing sieve analysis in a QC lab?
- Only verbal reporting
- Complete record of sample ID, sieve stack, sieve calibration, procedure, weights and calculations
- Only the final graph without raw data
- No documentation required
Correct Answer: Complete record of sample ID, sieve stack, sieve calibration, procedure, weights and calculations
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.
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