Kinematic viscosity MCQs With Answer

Kinematic viscosity MCQs With Answer

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Introduction: Kinematic viscosity MCQs With Answer are essential for B. Pharm students studying fluid flow, formulation science, and quality control. Kinematic viscosity—measured in stokes or centistokes—relates a fluid’s internal resistance to flow to its density and is distinct from dynamic viscosity. Understanding measurement techniques (capillary/Ostwald, Ubbelohde, Saybolt), temperature dependence, unit conversions, and practical implications in syrups, suspensions, emulsions, and coatings helps in formulation design and stability assessment. These focused MCQs cover calculations, instruments, standards (USP/ASTM), and typical pharmaceutical scenarios to strengthen conceptual and analytical skills. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the SI unit of kinematic viscosity?

  • Pascal-second (Pa·s)
  • Newton-second (N·s)
  • Square meter per second (m²/s)
  • Centipoise (cP)

Correct Answer: Square meter per second (m²/s)

Q2. Kinematic viscosity (ν) is related to dynamic viscosity (μ) and density (ρ) by which formula?

  • ν = μ × ρ
  • ν = μ / ρ
  • ν = ρ / μ
  • ν = μ + ρ

Correct Answer: ν = μ / ρ

Q3. Which instrument is commonly used to measure kinematic viscosity in the laboratory?

  • Brookfield viscometer
  • Ostwald (capillary) viscometer
  • Ubbelohde spectrophotometer
  • Tensiometer

Correct Answer: Ostwald (capillary) viscometer

Q4. Kinematic viscosity is often reported in centistokes. 1 cSt equals:

  • 1 × 10^-6 m²/s
  • 1 × 10^-4 m²/s
  • 1 × 10^-3 m²/s
  • 1 × 10^-2 m²/s

Correct Answer: 1 × 10^-6 m²/s

Q5. Which statement best describes kinematic viscosity?

  • It measures the fluid’s mass per unit volume.
  • It measures internal resistance to shear independent of density.
  • It measures internal resistance to flow normalized by density.
  • It measures surface tension effects in liquids.

Correct Answer: It measures internal resistance to flow normalized by density.

Q6. For Newtonian fluids, how does kinematic viscosity vary with shear rate?

  • It decreases with increasing shear rate.
  • It increases with increasing shear rate.
  • It remains constant regardless of shear rate.
  • It fluctuates unpredictably.

Correct Answer: It remains constant regardless of shear rate.

Q7. Which of the following viscometers measures kinematic viscosity by timing fluid flow through a capillary under gravity?

  • Rotational viscometer
  • Falling-ball viscometer
  • Capillary (Ostwald/Ubbelohde) viscometer
  • Vibrational viscometer

Correct Answer: Capillary (Ostwald/Ubbelohde) viscometer

Q8. Why is temperature control critical when measuring kinematic viscosity?

  • Temperature affects only the density, not viscosity.
  • Viscosity and density both change with temperature, altering kinematic viscosity significantly.
  • Temperature has negligible effect on kinematic viscosity in pharmaceuticals.
  • Temperature affects only color and odor, not viscosity.

Correct Answer: Viscosity and density both change with temperature, altering kinematic viscosity significantly.

Q9. Which equation commonly models the temperature dependence of viscosity?

  • Arrhenius or Andrade equation
  • Newton’s law of cooling
  • Van ’t Hoff equation
  • Gibbs free energy equation

Correct Answer: Arrhenius or Andrade equation

Q10. In pharmaceutical syrup formulation, why is kinematic viscosity important?

  • It determines only the drug’s solubility.
  • It affects pourability, mouthfeel, and suspended particle settling rate.
  • It controls only the color stability of the syrup.
  • It is irrelevant for oral liquid formulations.

Correct Answer: It affects pourability, mouthfeel, and suspended particle settling rate.

Q11. Which unit is used for dynamic viscosity in the CGS system that is often converted in calculations?

  • Pascal-second (Pa·s)
  • Poise (P)
  • Kelvin (K)
  • Stokes (St)

Correct Answer: Poise (P)

Q12. Relationship between stokes and centistokes is:

  • 1 St = 100 cSt
  • 1 St = 10 cSt
  • 1 St = 1000 cSt
  • 1 St = 0.01 cSt

Correct Answer: 1 St = 100 cSt

Q13. The Reynolds number using kinematic viscosity is defined as:

  • Re = ρ v L / μ
  • Re = v L / ν
  • Re = μ / (ρ v L)
  • Re = ν / (v L)

Correct Answer: Re = v L / ν

Q14. Which USP or ASTM practice is relevant for kinematic viscosity measurement?

  • USP chapters on dissolution testing
  • ASTM D445 for kinematic viscosity of transparent and opaque liquids
  • USP monographs on microbial limits
  • ASTM methods for particle size only

Correct Answer: ASTM D445 for kinematic viscosity of transparent and opaque liquids

Q15. If a liquid has dynamic viscosity 1.2 mPa·s and density 1.0 g/cm³, its kinematic viscosity in cSt is approximately:

  • 0.12 cSt
  • 1.2 cSt
  • 12 cSt
  • 120 cSt

Correct Answer: 1.2 cSt

Q16. Which phenomenon is directly influenced by kinematic viscosity in suspensions?

  • Drug degradation kinetics
  • Rate of particle sedimentation
  • pH stability
  • Microbial growth

Correct Answer: Rate of particle sedimentation

Q17. Which viscosity term is independent of density?

  • Kinematic viscosity
  • Dynamic viscosity
  • Specific viscosity
  • Relative density

Correct Answer: Dynamic viscosity

Q18. Which viscometer type is preferred for non-Newtonian formulations like gels?

  • Capillary viscometer
  • Rotational (Brookfield) viscometer
  • U-tube manometer
  • Mercury viscometer

Correct Answer: Rotational (Brookfield) viscometer

Q19. The Andrade equation relates viscosity to temperature using which functional form?

  • Linear increase with temperature
  • Arrhenius-type exponential relationship
  • Logarithmic decrease independent of activation energy
  • Quadratic dependency

Correct Answer: Arrhenius-type exponential relationship

Q20. Which sample preparation step is critical before measuring kinematic viscosity?

  • Diluting to extreme concentrations always
  • Removing air bubbles and equilibrating to measurement temperature
  • Adding preservative agents
  • Heating to boiling point

Correct Answer: Removing air bubbles and equilibrating to measurement temperature

Q21. In capillary viscometry, the flow time is proportional to:

  • Density only
  • Dynamic viscosity divided by density (kinematic viscosity)
  • Surface tension only
  • Concentration of solute only

Correct Answer: Dynamic viscosity divided by density (kinematic viscosity)

Q22. Which factor does NOT typically affect kinematic viscosity of a pharmaceutical liquid?

  • Temperature
  • Concentration of solutes
  • Applied magnetic field (normal conditions)
  • Presence of suspended particles

Correct Answer: Applied magnetic field (normal conditions)

Q23. Saybolt viscometer reports which viscosity units often used in industry?

  • Seconds (Saybolt Universal Seconds)
  • Centistokes
  • Pascal-seconds
  • Stokes

Correct Answer: Seconds (Saybolt Universal Seconds)

Q24. Which conversion is correct: 1 mPa·s equals how many cP?

  • 1 mPa·s = 10 cP
  • 1 mPa·s = 1 cP
  • 1 mPa·s = 0.1 cP
  • 1 mPa·s = 100 cP

Correct Answer: 1 mPa·s = 1 cP

Q25. Kinematic viscosity of water at 20°C is approximately:

  • 1 cSt
  • 10 cSt
  • 0.1 cSt
  • 100 cSt

Correct Answer: 1 cSt

Q26. Which of the following describes viscosity index (VI)?

  • A measure of fluid’s color stability
  • A measure of how viscosity changes with temperature
  • A measure of density variation with pressure
  • A measure of pH sensitivity

Correct Answer: A measure of how viscosity changes with temperature

Q27. In fluid dynamics, lower kinematic viscosity typically promotes:

  • Lamination and lower tendency to turbulence at given velocity and dimension
  • Turbulence more easily at given velocity and dimension
  • Higher drag always
  • Instant solidification

Correct Answer: Turbulence more easily at given velocity and dimension

Q28. For an emulsion, an increase in kinematic viscosity generally will:

  • Increase creaming and phase separation rate
  • Reduce droplet coalescence by improving physical stability
  • Increase drug degradation rate exclusively
  • Convert the emulsion to a gas

Correct Answer: Reduce droplet coalescence by improving physical stability

Q29. Which liquid would likely have the highest kinematic viscosity at room temperature?

  • Water
  • Glycerin
  • Ethanol
  • Hexane

Correct Answer: Glycerin

Q30. When converting dynamic viscosity (mPa·s) to kinematic viscosity (cSt) for aqueous solutions, you typically divide by:

  • Density in g/cm³
  • Viscosity index
  • Temperature in °C
  • Concentration percentage

Correct Answer: Density in g/cm³

Q31. Which error source is common in capillary viscometry?

  • Neglecting gravitational acceleration changes
  • Timing errors and incorrect temperature control
  • Magnetic interference
  • Viscosity index miscalculation only

Correct Answer: Timing errors and incorrect temperature control

Q32. In quality control, reporting kinematic viscosity at a specified temperature (e.g., 40°C) ensures:

  • Comparability between batches and instruments
  • That density is constant across samples
  • pH remains unchanged
  • Microbial growth is prevented

Correct Answer: Comparability between batches and instruments

Q33. The presence of high molecular weight polymers in a solution typically causes:

  • Decrease in kinematic viscosity
  • Increase in kinematic viscosity and potential non-Newtonian behavior
  • No change in viscosity
  • Evaporation of the solvent

Correct Answer: Increase in kinematic viscosity and potential non-Newtonian behavior

Q34. Which is true about kinematic viscosity measurement for opaque or particulate-laden liquids?

  • Capillary viscometers cannot be used; use methods like rotational viscometry or calibrated relative methods.
  • Capillary viscometers always work irrespective of opacity.
  • Opacity affects only density measurements.
  • Opaque liquids have zero kinematic viscosity.

Correct Answer: Capillary viscometers cannot be used; use methods like rotational viscometry or calibrated relative methods.

Q35. The term “centistokes” is most closely associated with which physical quantity?

  • Dynamic viscosity
  • Kinematic viscosity
  • Density
  • Surface tension

Correct Answer: Kinematic viscosity

Q36. When validating a viscometer, one should:

  • Ignore calibration fluids and proceed directly to samples
  • Use certified viscosity standards at the same temperature range as samples
  • Use any liquid and assume instrument is accurate
  • Calibrate only once when purchased

Correct Answer: Use certified viscosity standards at the same temperature range as samples

Q37. In laminar flow through a pipe, an increase in kinematic viscosity will generally:

  • Decrease the pressure drop for a given flow rate
  • Increase the pressure drop for a given flow rate
  • Not affect flow resistance
  • Instantly cause turbulent flow

Correct Answer: Increase the pressure drop for a given flow rate

Q38. Which pharmaceutical process requires precise knowledge of kinematic viscosity for spray formation?

  • Tablet compression
  • Aerosol and spray nozzle atomization
  • Lyophilization
  • Sterility testing

Correct Answer: Aerosol and spray nozzle atomization

Q39. How does dissolved solids concentration typically affect kinematic viscosity of aqueous solutions?

  • Increased concentration usually increases kinematic viscosity
  • Increased concentration always decreases kinematic viscosity
  • Concentration has no effect
  • It only affects color, not viscosity

Correct Answer: Increased concentration usually increases kinematic viscosity

Q40. Which term describes a fluid whose viscosity decreases with increasing shear rate?

  • Newtonian
  • Dilatant (shear-thickening)
  • Pseudoplastic (shear-thinning)
  • Bingham plastic exclusively

Correct Answer: Pseudoplastic (shear-thinning)

Q41. Kinematic viscosity plays a role in which aspect of topical ointment performance?

  • Drug chemical structure only
  • Spreadability and residence time on skin
  • Color fastness only
  • Sterility of ointment

Correct Answer: Spreadability and residence time on skin

Q42. Which of the following is a direct method to measure kinematic viscosity?

  • Measuring torque on a spindle
  • Timing flow through a calibrated capillary at constant temperature
  • Measuring electrical conductivity
  • Determining refractive index

Correct Answer: Timing flow through a calibrated capillary at constant temperature

Q43. When reporting kinematic viscosity in a lab notebook, you should always include:

  • Only the value and nothing else
  • Value, temperature, instrument type, and calibration status
  • Only the instrument brand
  • The room color and humidity only

Correct Answer: Value, temperature, instrument type, and calibration status

Q44. In a falling-sphere viscometer, what additional property is needed along with fall time to calculate kinematic viscosity?

  • Sphere’s color
  • Sphere size and density, and liquid density
  • pH of the liquid only
  • Magnetic susceptibility

Correct Answer: Sphere size and density, and liquid density

Q45. Which practice helps reduce systematic error in viscosity measurement?

  • Varying temperature during measurement
  • Using unclean viscometer tubes
  • Ensuring temperature equilibration and using clean, calibrated equipment
  • Measuring without calibration standards

Correct Answer: Ensuring temperature equilibration and using clean, calibrated equipment

Q46. For high-viscosity ointment bases, which method is most useful to assess flow behavior?

  • Capillary viscometer at low shear
  • Rotational rheometer or rotational viscometer at controlled shear
  • Conductivity meter
  • UV spectrophotometry

Correct Answer: Rotational rheometer or rotational viscometer at controlled shear

Q47. A formulation scientist wants to reduce sedimentation in a suspension; they should:

  • Reduce the kinematic viscosity of the medium
  • Increase kinematic viscosity moderately to slow particle settling
  • Remove all viscosity modifiers
  • Increase temperature to boiling

Correct Answer: Increase kinematic viscosity moderately to slow particle settling

Q48. Which relationship helps convert dynamic viscosity (μ in Pa·s) to kinematic viscosity (ν in m²/s)?

  • ν = μ × ρ
  • ν = μ / ρ
  • ν = μ + ρ
  • ν = ρ / μ

Correct Answer: ν = μ / ρ

Q49. During formulation scale-up, why monitor kinematic viscosity?

  • To ensure sensory properties and processability remain consistent at larger scale
  • It is unnecessary during scale-up
  • Only color changes matter during scale-up
  • To increase microbial contamination intentionally

Correct Answer: To ensure sensory properties and processability remain consistent at larger scale

Q50. Which statement is true about kinematic viscosity and drug delivery performance?

  • Kinematic viscosity has no impact on drug release from topical or liquid dosage forms.
  • Appropriate kinematic viscosity influences release rate, spreadability, and stability of dosage forms.
  • Only chemical additives control drug release; viscosity is irrelevant.
  • Higher kinematic viscosity always improves drug bioavailability.

Correct Answer: Appropriate kinematic viscosity influences release rate, spreadability, and stability of dosage forms.

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