The comparative properties of colloids MCQs with answer provide B. Pharm students a focused, exam-ready review of colloidal systems, stability, and pharmaceutical applications. This introduction covers key concepts—particle size, lyophilic vs lyophobic behavior, Tyndall effect, Brownian motion, zeta potential, coagulation, protective colloids, and methods of preparation and purification—so you can compare properties across colloidal types. Emphasis on pharmaceutical relevance (suspensions, emulsions, nanoparticles, drug delivery) ensures practical understanding. The language is simple, informative, and keyword-rich to boost revision and retention. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the typical particle size range usually accepted for colloidal systems?
- 1 nm to 1 μm
- 1 μm to 10 μm
- 10 nm to 100 nm only
- 0.1 mm to 1 mm
Correct Answer: 1 nm to 1 μm
Q2. Which property causes colloidal dispersions to scatter visible light and show the Tyndall effect?
- Presence of dissolved electrolytes
- Particle size comparable to wavelength of light
- High viscosity of medium
- Low surface tension
Correct Answer: Particle size comparable to wavelength of light
Q3. Brownian motion in colloidal particles is primarily due to:
- Gravity acting on particles
- Thermal collisions with solvent molecules
- Electrostatic attraction between particles
- Magnetic fields in medium
Correct Answer: Thermal collisions with solvent molecules
Q4. Lyophilic colloids are characterized by which feature?
- Poor affinity for solvent and irreversible coagulation
- Strong affinity for solvent and stability with reversible coagulation
- Always electrically neutral
- Cannot be stabilized by protective colloids
Correct Answer: Strong affinity for solvent and stability with reversible coagulation
Q5. Which of the following is an example of a protective colloid used in pharmaceutical formulations?
- Sodium chloride
- Gelatin
- Hydrochloric acid
- Calcium carbonate
Correct Answer: Gelatin
Q6. The Schulze–Hardy rule relates coagulation power of ions to:
- Size of the colloidal particles only
- Valency of the counter-ion
- Temperature of the medium
- pH only
Correct Answer: Valency of the counter-ion
Q7. Which measurement indicates colloidal stability related to electrical charge at the shear plane?
- Viscosity
- Zeta potential
- Boiling point elevation
- Mass density
Correct Answer: Zeta potential
Q8. According to DLVO theory, the two main interactions determining colloidal stability are:
- Hydrogen bonding and covalent bonding
- Van der Waals attraction and electrical double-layer repulsion
- Gravitational attraction and magnetic repulsion
- Viscous drag and thermal conduction
Correct Answer: Van der Waals attraction and electrical double-layer repulsion
Q9. Which colloid type is most likely to form micelles at or above the CMC?
- Lyophilic polymer colloids
- Amphiphilic surfactant solutions
- Inorganic sols like gold sol
- Colloidal gases
Correct Answer: Amphiphilic surfactant solutions
Q10. In pharmaceutical suspensions, which property of colloidal particles helps prevent rapid sedimentation?
- Large particle size (>10 μm)
- Brownian motion and low density difference
- High ionic strength of medium
- Absence of surfactant
Correct Answer: Brownian motion and low density difference
Q11. Dialysis is used in colloid purification to remove:
- Colloidal particles based on size
- Small ions and low molecular weight solutes
- All organic solvents
- Large polymeric stabilizers
Correct Answer: Small ions and low molecular weight solutes
Q12. Which method is a condensation method for preparing colloids?
- Emulsification
- Chemical reduction of metal salts
- Mechanical grinding to micron size
- Evaporation of solvent only
Correct Answer: Chemical reduction of metal salts
Q13. The coagulation value of an electrolyte for a given colloid is defined as the minimum concentration that:
- Prevents dialysis
- Induces rapid coagulation within a specified time
- Enhances Brownian motion
- Increases viscosity indefinitely
Correct Answer: Induces rapid coagulation within a specified time
Q14. A higher absolute zeta potential (e.g., > ±30 mV) generally indicates:
- Increased colloidal instability
- Greater electrostatic stabilization and stability
- Higher molecular weight of particles
- Immediate precipitation regardless of conditions
Correct Answer: Greater electrostatic stabilization and stability
Q15. Which statement correctly contrasts sols and gels?
- Sols are semi-solid; gels are fluid dispersions
- Sols are fluid dispersions of colloidal particles; gels are semi-solid networks trapping liquid
- Sols are always lyophilic; gels are always lyophobic
- Sols cannot be used in pharmaceuticals while gels can
Correct Answer: Sols are fluid dispersions of colloidal particles; gels are semi-solid networks trapping liquid
Q16. Electrophoresis in colloids refers to:
- Movement of solvent relative to fixed particles under gravity
- Migration of charged colloidal particles under an applied electric field
- Formation of micelles due to electric current
- Heat generation in colloids under current
Correct Answer: Migration of charged colloidal particles under an applied electric field
Q17. Which of the following is a lyophobic colloid example commonly relevant in pharmacy?
- Starch sol
- Gold sol
- Gelatin sol
- Synthetic polymer sol like PVP
Correct Answer: Gold sol
Q18. Flocculation differs from coagulation in that flocs are generally:
- Irreversibly compacted aggregates
- Loosely bound aggregates that can be redispersed
- Only observed in gas colloids
- Always chemically bonded
Correct Answer: Loosely bound aggregates that can be redispersed
Q19. Which parameter is most directly reduced when a protective colloid adsorbs on lyophobic particles?
- Particle core density
- Interfacial free energy and tendency to coagulate
- Optical refractive index of solvent
- Number of surfactant molecules in solution
Correct Answer: Interfacial free energy and tendency to coagulate
Q20. Which of these techniques separates colloidal particles based on sedimentation under high centrifugal force?
- Dialysis
- Ultracentrifugation
- Gel filtration chromatography only
- Thin layer chromatography
Correct Answer: Ultracentrifugation
Q21. What is a pharmaceutical advantage of nanosized colloidal drug carriers?
- Always cause immediate immune reaction
- Improved bioavailability and targeted delivery
- Poor solubility compared with bulk drug
- Lower surface area leading to slower release
Correct Answer: Improved bioavailability and targeted delivery
Q22. Which phenomenon explains why very small colloidal particles do not settle quickly under gravity?
- Schulze–Hardy rule
- Brownian motion counteracting sedimentation
- Electrolyte addition
- High ionic strength of medium
Correct Answer: Brownian motion counteracting sedimentation
Q23. In an oil-in-water (O/W) emulsion used in topical formulations, the dispersed phase and continuous phase are:
- Oil dispersed in water as continuous
- Water dispersed in oil continuous
- Both phases are solids
- Gas dispersed in liquid
Correct Answer: Oil dispersed in water as continuous
Q24. Which of the following increases the rate of coagulation of a lyophobic colloid?
- Addition of a highly charged counter-ion of opposite sign
- Lowering temperature to absolute zero
- Adding large amounts of protective colloid
- Diluting to infinite volume
Correct Answer: Addition of a highly charged counter-ion of opposite sign
Q25. The phenomenon of peptization refers to:
- Conversion of a hydrated gel into a sol
- Breaking a precipitate into colloidal particles by adding appropriate electrolyte or solvent
- Complete evaporation of colloid to dryness
- Formation of micelles from surfactants
Correct Answer: Breaking a precipitate into colloidal particles by adding appropriate electrolyte or solvent
Q26. Which optical technique is commonly used to estimate particle size distribution in colloids by light scattering?
- UV-Vis spectroscopy only
- Dynamic light scattering (DLS)
- Infrared spectroscopy
- Polarimetry
Correct Answer: Dynamic light scattering (DLS)
Q27. The term “colloid osmotic pressure” is most relevant to which biological/pharmaceutical system?
- Gas absorption in lungs
- Plasma proteins maintaining oncotic pressure
- Solid tablets dissolution
- Dental enamel remineralization
Correct Answer: Plasma proteins maintaining oncotic pressure
Q28. Which of the following lowers the interfacial tension and stabilizes emulsions by forming an interfacial film?
- Strong electrolytes like NaCl
- Surfactants (emulsifiers)
- Pure water only
- Insoluble salts
Correct Answer: Surfactants (emulsifiers)
Q29. Which is true about micelles compared to typical colloidal particles?
- Micelles are usually smaller and formed by self-assembly of surfactant molecules
- Micelles are always larger than colloidal particles
- Micelles cannot solubilize hydrophobic drugs
- Micelles are crystalline solids
Correct Answer: Micelles are usually smaller and formed by self-assembly of surfactant molecules
Q30. Which term best describes a colloidal system where gas is dispersed in liquid (like foams)?
- Sols
- Emulsions
- Aerosols/foams
- Gels
Correct Answer: Aerosols/foams
Q31. The primary role of a steric stabilizer in colloids is to:
- Increase net charge and electrostatic repulsion only
- Create a physical barrier via adsorbed polymer chains to prevent aggregation
- Reduce the solubility of the dispersed phase
- Enhance gravitational settling
Correct Answer: Create a physical barrier via adsorbed polymer chains to prevent aggregation
Q32. Which electrolyte would, according to Schulze–Hardy rule, have the strongest coagulating effect on a negatively charged colloid?
- Na+ (monovalent)
- Ca2+ (divalent)
- Al3+ (trivalent)
- K+ (monovalent)
Correct Answer: Al3+ (trivalent)
Q33. Which property distinguishes a true solution from a colloidal dispersion?
- True solutions show the Tyndall effect while colloids do not
- Colloids scatter light (Tyndall effect); true solutions do not
- Colloids pass through semipermeable membranes but true solutions do not
- True solutions contain suspended visible particles
Correct Answer: Colloids scatter light (Tyndall effect); true solutions do not
Q34. What is the effect of increasing temperature on Brownian motion of colloidal particles?
- Brownian motion decreases with temperature
- Brownian motion increases as thermal energy increases
- Brownian motion is independent of temperature
- Brownian motion stops at moderate temperatures
Correct Answer: Brownian motion increases as thermal energy increases
Q35. A colloidal dispersion that shows reversible coagulation upon changing conditions is more likely to be:
- Lyophilic
- Lyophobic and permanently aggregated
- Crystalline solid
- Non-polar gas
Correct Answer: Lyophilic
Q36. Which analysis technique measures electrophoretic mobility to infer zeta potential?
- Ultraviolet spectroscopy
- Electrophoretic light scattering (ELS)
- Titration only
- Mass spectrometry
Correct Answer: Electrophoretic light scattering (ELS)
Q37. Which statement about emulsions used in topical drug delivery is correct?
- Oil-in-water emulsions are generally greasier than water-in-oil
- Water-in-oil emulsions are better for occlusive and moisturizing effects
- Emulsions never require preservatives
- All emulsions are thermodynamically stable
Correct Answer: Water-in-oil emulsions are better for occlusive and moisturizing effects
Q38. Which parameter is decreased when colloidal particles aggregate into larger flocs?
- Effective surface area per unit mass
- Particle mass
- Core composition
- Density of solvent
Correct Answer: Effective surface area per unit mass
Q39. Hydrosols are colloids where the continuous phase is:
- Oil
- Water
- Gas
- Solid
Correct Answer: Water
Q40. Which factor does NOT directly affect the rate of coagulation of colloidal particles?
- Concentration and valency of added electrolytes
- Temperature of the system
- Nature of protective colloids present
- Color of the colloidal particles
Correct Answer: Color of the colloidal particles
Q41. In pharmaceutical colloids, adsorption of drug molecules onto colloidal carriers primarily depends on:
- Interfacial area, surface chemistry, and affinity
- Only the pH of the solvent
- Gravity exclusively
- The color of the drug
Correct Answer: Interfacial area, surface chemistry, and affinity
Q42. Which statement best describes the concept of steric stabilization versus electrostatic stabilization?
- Steric uses adsorbed polymer layers; electrostatic uses surface charge to prevent aggregation
- Steric increases ionic strength; electrostatic adds polymers
- They are identical phenomena with different names
- Steric only works in non-polar solvents while electrostatic only works under vacuum
Correct Answer: Steric uses adsorbed polymer layers; electrostatic uses surface charge to prevent aggregation
Q43. Which colloidal dosage form is commonly used for pulmonary delivery as an aerosol?
- Suspension aerosols
- Tablet compressions
- Solid implants
- Bulk powders not aerosolized
Correct Answer: Suspension aerosols
Q44. The phenomenon where an adsorbed layer of ions or molecules around a colloidal particle forms a charged environment is called:
- Coacervation
- Electrical double layer
- Peptization
- Emulsification
Correct Answer: Electrical double layer
Q45. Which of the following increases solubilization of a poorly water-soluble drug in colloidal carriers?
- Reducing interfacial area
- Using surfactant micelles or nanoparticle carriers
- Avoiding any stabilizers
- Increasing particle aggregation intentionally
Correct Answer: Using surfactant micelles or nanoparticle carriers
Q46. The Hardy–Schulz law relates colloidal stability to:
- Concentration of protective colloid used only
- Effect of increasing amount of dispersed phase on stability in presence of coagulant
- Color change with pH
- Melting point of colloid
Correct Answer: Effect of increasing amount of dispersed phase on stability in presence of coagulant
Q47. Which of the following is TRUE about dialysis of colloidal solutions?
- Dialysis removes colloidal particles but retains small ions
- Dialysis uses semipermeable membrane allowing small solutes to pass while retaining colloids
- Dialysis requires addition of coagulants to work
- Dialysis changes particle size into macroscopic crystals
Correct Answer: Dialysis uses semipermeable membrane allowing small solutes to pass while retaining colloids
Q48. What role does pH play in colloidal stability of protein-based nanoparticles?
- No role; proteins are pH-insensitive
- Alters surface charge, approaching isoelectric point reduces stability and promotes aggregation
- Only affects color but not stability
- Makes particles magnetic
Correct Answer: Alters surface charge, approaching isoelectric point reduces stability and promotes aggregation
Q49. Which method is commonly used to assess the presence of Tyndall scattering in a colloidal sample?
- Passing a beam of light through the sample and observing scattered light
- Measuring boiling point elevation only
- Weighing the sample on a balance
- Measuring electrical conductivity at zero field
Correct Answer: Passing a beam of light through the sample and observing scattered light
Q50. In designing a stable pharmaceutical colloid for intravenous use, which factor is most critical?
- Ensuring particles aggregate quickly after administration
- Biocompatibility, sterility, appropriate size, and stability (zeta potential/steric stabilizers)
- Maximizing color intensity of the formulation
- Using high concentrations of toxic electrolytes for coagulation
Correct Answer: Biocompatibility, sterility, appropriate size, and stability (zeta potential/steric stabilizers)
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