Physics of tablet compression MCQs With Answer

Physics of tablet compression MCQs With Answer

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Physics of Tablet Compression MCQs With Answer offers a focused self-assessment tool for M. Pharm students studying Modern Pharmaceutics (MPH 103T). This quiz emphasizes the mechanics of powder compression, including particle rearrangement, plastic deformation, brittle fracture, densification kinetics, and how tooling, speed, and lubrication influence tablet properties. You will encounter questions on Heckel and Kawakita analyses, dwell time, elastic recovery, die-wall friction, work of compaction, tensile strength models, and bonding mechanisms. Each item is designed to connect theory with practice—linking compaction profiles to defects like capping/lamination, and material attributes to performance outcomes. Use this set to deepen your conceptual grasp and to develop a physics-based intuition for robust tablet design and scale-up.

Q1. In Heckel analysis, a lower yield pressure (Py) for a powder indicates which compaction behavior?

  • Greater tendency for plastic deformation under pressure
  • Greater tendency for brittle fracture with minimal plastic flow
  • Higher elastic recovery after ejection
  • Higher die-wall friction during ejection

Correct Answer: Greater tendency for plastic deformation under pressure

Q2. In the Kawakita equation for compressibility, the parameter “a” primarily represents:

  • Maximum fractional reduction in powder bed volume (total compressibility/initial porosity)
  • Yield pressure for plastic flow during compaction
  • Elastic recovery of the tablet after ejection
  • Tensile strength of the compact at zero porosity

Correct Answer: Maximum fractional reduction in powder bed volume (total compressibility/initial porosity)

Q3. Increasing dwell time at a given peak force on a rotary press generally leads to:

  • Greater plastic deformation and stronger tablets
  • Higher ejection force due to increased die-wall adhesion
  • Increased lamination due to rapid decompression
  • Increased porosity and reduced tensile strength

Correct Answer: Greater plastic deformation and stronger tablets

Q4. For a plastically deforming excipient, increasing the compression speed (higher strain rate) typically causes:

  • Reduced plastic deformation due to strain-rate sensitivity
  • Increased fragmentation with creation of fresh surfaces
  • Lower elastic recovery leading to fewer capping events
  • Unchanged interparticle bonding area

Correct Answer: Reduced plastic deformation due to strain-rate sensitivity

Q5. In the diametral compression (Brazilian) test, the tensile strength of a flat-faced tablet increases when:

  • Breaking force increases at constant diameter and thickness
  • Tablet diameter increases at constant breaking force
  • Tablet thickness increases at constant breaking force
  • Breaking force decreases at constant dimensions

Correct Answer: Breaking force increases at constant diameter and thickness

Q6. The plastic work of compaction during tableting is best described as:

  • The area between the loading and unloading curves in the force–displacement profile
  • The total area under the loading curve alone
  • The area under the unloading curve alone
  • The product of peak force and dwell time

Correct Answer: The area between the loading and unloading curves in the force–displacement profile

Q7. High die-wall friction during compaction most directly leads to:

  • Greater axial density gradients within the tablet
  • Decreased ejection force and smoother ejection
  • Improved tensile strength due to enhanced bonding
  • Elimination of capping during decompression

Correct Answer: Greater axial density gradients within the tablet

Q8. Which phenomenon is most directly associated with capping immediately after ejection?

  • High axial elastic recovery of the compact
  • High plastic deformation at peak force
  • Low die-wall friction due to optimal lubrication
  • High residual porosity in the compact core

Correct Answer: High axial elastic recovery of the compact

Q9. In the context of mechanical percolation in tablets, the percolation threshold refers to:

  • A critical consolidation level where a continuous bonding network forms
  • The pressure at which elastic recovery begins
  • The minimum dwell time needed for plastic flow
  • The onset of fragmentation for brittle excipients

Correct Answer: A critical consolidation level where a continuous bonding network forms

Q10. Fragmentation of brittle particles during compaction primarily enhances tablet strength by:

  • Creating fresh surfaces and increasing interparticle contact area
  • Increasing elastic recovery and relieving internal stress
  • Reducing die-wall friction by producing finer particles
  • Lowering the true density of the powder bed

Correct Answer: Creating fresh surfaces and increasing interparticle contact area

Q11. A powder exhibiting a higher effective Poisson’s ratio during compaction is more likely to:

  • Undergo greater radial expansion and exert higher die-wall stress
  • Exhibit lower ejection force due to better lubrication
  • Show reduced risk of lamination upon decompression
  • Have no effect on tooling wear and die stresses

Correct Answer: Undergo greater radial expansion and exert higher die-wall stress

Q12. A compaction simulator in tablet R&D is primarily used to:

  • Reproduce industrial press force–time profiles at laboratory scale
  • Measure particle size distribution with laser diffraction
  • Perform dry granulation via roller compaction
  • Apply polymeric film coats to compressed tablets

Correct Answer: Reproduce industrial press force–time profiles at laboratory scale

Q13. The dominant bonding mechanism in most directly compressed tablets is:

  • Intermolecular forces (van der Waals and hydrogen bonding) at interparticle contacts
  • Covalent bond formation between excipient molecules
  • Ionic bonding between drug and punch steel surfaces
  • Magnetic forces aligning particulate domains

Correct Answer: Intermolecular forces (van der Waals and hydrogen bonding) at interparticle contacts

Q14. In the Heckel plot, the intercept “A” primarily reflects:

  • The initial relative density of the powder bed (packing before significant plastic deformation)
  • The tensile strength of the compact at zero porosity
  • The coefficient of die-wall friction during ejection
  • The Kawakita pressure parameter of rearrangement

Correct Answer: The initial relative density of the powder bed (packing before significant plastic deformation)

Q15. Increasing magnesium stearate level and/or blending time most consistently results in:

  • Decrease in tablet tensile strength due to surface coverage and inhibited bonding
  • Increase in fragmentation tendency of brittle components
  • Increase in moisture uptake of the compact matrix
  • Higher sticking tendency to punch faces

Correct Answer: Decrease in tablet tensile strength due to surface coverage and inhibited bonding

Q16. Pre-densification by roller compaction commonly affects downstream tableting by:

  • Reducing plasticity via work hardening, necessitating higher main compression forces
  • Eliminating the need for lubrication during ejection
  • Guaranteeing higher tensile strength at any given porosity
  • Preventing capping irrespective of press speed

Correct Answer: Reducing plasticity via work hardening, necessitating higher main compression forces

Q17. Using punches with a larger head flat (at constant turret speed and peak force) will:

  • Increase dwell time and promote greater plastic deformation
  • Reduce dwell time and limit plastic flow
  • Reduce sticking solely by changing die clearance
  • Increase compact porosity at a given force

Correct Answer: Increase dwell time and promote greater plastic deformation

Q18. According to the Ryshkewitch–Duckworth relationship, tablet tensile strength typically:

  • Decreases exponentially with increasing porosity
  • Increases linearly with porosity
  • Is independent of porosity above the percolation threshold
  • Increases with the square of porosity

Correct Answer: Decreases exponentially with increasing porosity

Q19. Which intervention best decreases ejection force without markedly compromising tablet strength?

  • Polishing die wall surfaces and using an optimal (not excessive) lubricant level
  • Increasing compaction speed to reduce residence time
  • Promoting higher elastic recovery to lower wall pressure
  • Switching to very coarse particles regardless of material properties

Correct Answer: Polishing die wall surfaces and using an optimal (not excessive) lubricant level

Q20. The primary purpose of the precompression stage on a rotary tablet press is to:

  • Expel entrapped air and initiate particle rearrangement before main compression
  • Increase final tablet hardness directly by raising peak force
  • Improve lubrication efficiency at the die–wall interface
  • Reduce ejection force by decreasing radial recovery

Correct Answer: Expel entrapped air and initiate particle rearrangement before main compression

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