MCQ Quiz: Emulsions

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Emulsions are essential biphasic dosage forms, skillfully designed to deliver oily or poorly water-soluble drugs in a uniform liquid preparation. For B.Pharm students, mastering the art and science of emulsion formulation—from selecting the right emulsifier using the HLB system to overcoming complex stability challenges like creaming and cracking—is a fundamental skill. This quiz will test your knowledge of the classification, preparation, and evaluation of these critical pharmaceutical systems.

  1. A pharmaceutical emulsion is a biphasic system consisting of two:
    • Miscible liquids
    • Immiscible liquids
    • Soluble solids
    • Gases in a liquid
    Answer: Immiscible liquids
  2. An agent used to stabilize an emulsion is called a(n):
    • Suspending agent
    • Wetting agent
    • Emulsifying agent
    • Flocculating agent
    Answer: Emulsifying agent
  3. In an oil-in-water (o/w) emulsion, the dispersed phase is:
    • Water
    • Oil
    • A solid
    • A gas
    Answer: Oil
  4. The HLB (Hydrophile-Lipophile Balance) system is used to:
    • Select a suitable emulsifier
    • Determine the particle size
    • Measure the viscosity
    • Identify the type of emulsion
    Answer: Select a suitable emulsifier
  5. Which test for identifying the type of emulsion is based on the principle that an emulsion is miscible with its continuous phase?
    • Dye solubility test
    • Conductivity test
    • Dilution test
    • Viscosity test
    Answer: Dilution test
  6. The upward movement of dispersed droplets to form a concentrated layer at the surface of an emulsion is called:
    • Sedimentation
    • Coalescence
    • Creaming
    • Breaking
    Answer: Creaming
  7. The complete and irreversible separation of the dispersed phase from the continuous phase is known as:
    • Creaming
    • Phase inversion
    • Cracking or Breaking
    • Coalescence
    Answer: Cracking or Breaking
  8. In a water-in-oil (w/o) emulsion, the continuous phase is:
    • Water
    • Oil
    • The emulsifier
    • A solid
    Answer: Oil
  9. An emulsifying agent with a low HLB value (3-6) is suitable for preparing a(n):
    • o/w emulsion
    • w/o emulsion
    • Suspension
    • Solution
    Answer: w/o emulsion
  10. The “Dry Gum” method of preparing emulsions is also known as the:
    • English method
    • Bottle method
    • Continental method
    • Beaker method
    Answer: Continental method
  11. Which of the following is an example of a natural emulsifying agent?
    • Sodium lauryl sulfate
    • Polysorbate 80 (Tween 80)
    • Acacia
    • Cetyl alcohol
    Answer: Acacia
  12. The merging of smaller droplets to form larger droplets in an emulsion is termed:
    • Creaming
    • Breaking
    • Phase inversion
    • Coalescence
    Answer: Coalescence
  13. A w/o emulsion will conduct electricity:
    • Very well
    • Poorly or not at all
    • Only when heated
    • Better than an o/w emulsion
    Answer: Poorly or not at all
  14. What is the primary function of an emulsifying agent?
    • To reduce the interfacial tension between the two immiscible liquids
    • To increase the density of the dispersed phase
    • To dissolve one phase in the other
    • To act as a preservative
    Answer: To reduce the interfacial tension between the two immiscible liquids
  15. The “Wet Gum” method of preparing emulsions is also known as the:
    • Continental method
    • English method
    • Forbes bottle method
    • In situ soap method
    Answer: English method
  16. The phenomenon where an emulsion changes from o/w to w/o is called:
    • Breaking
    • Creaming
    • Coalescence
    • Phase inversion
    Answer: Phase inversion
  17. Which stability problem in an emulsion is considered reversible?
    • Breaking
    • Coalescence
    • Creaming
    • Phase inversion
    Answer: Creaming
  18. The fixed oil:water:gum ratio for the primary emulsion in the dry gum method is:
    • 1:2:4
    • 2:4:1
    • 4:2:1
    • 1:1:1
    Answer: 4:2:1
  19. If a drop of an emulsion mixes readily with an oil-soluble dye, the emulsion is likely a(n):
    • o/w type
    • w/o type
    • Multiple emulsion
    • Suspension
    Answer: w/o type
  20. Which of the following is a synthetic emulsifying agent?
    • Gelatin
    • Acacia
    • Tragacanth
    • Sodium lauryl sulfate
    Answer: Sodium lauryl sulfate
  21. The internal phase of an emulsion is also called the:
    • Continuous phase
    • External phase
    • Dispersed phase
    • Homogenous phase
    Answer: Dispersed phase
  22. According to Bancroft’s rule, the phase in which the emulsifier is more soluble will become the:
    • Dispersed phase
    • Continuous phase
    • Internal phase
    • Precipitate
    Answer: Continuous phase
  23. The Bottle method is suitable for preparing emulsions containing:
    • Viscous oils
    • Volatile and non-viscous oils
    • Solid fats
    • Gums
    Answer: Volatile and non-viscous oils
  24. Which physical property is a good indicator of the type of emulsion (o/w vs w/o)?
    • Color
    • Odor
    • Electrical conductivity
    • pH
    Answer: Electrical conductivity
  25. The primary mechanism by which emulsifiers work is by forming a(n) ______ around the dispersed droplets.
    • Monomolecular film
    • Multimolecular film
    • Solid particle film
    • All of the above
    Answer: All of the above
  26. Which of the following is a semi-solid emulsifying agent?
    • Acacia
    • Gelatin
    • Cetyl alcohol
    • Tween 20
    Answer: Cetyl alcohol
  27. A key difference between creaming and breaking is that:
    • Creaming is reversible, while breaking is irreversible.
    • Creaming is irreversible, while breaking is reversible.
    • Creaming involves droplet merging.
    • Breaking involves droplet rising.
    Answer: Creaming is reversible, while breaking is irreversible.
  28. The fixed oil:water:gum ratio for the primary emulsion in the wet gum method is:
    • 4:2:1
    • 2:4:1
    • 1:2:4
    • The ratio is not fixed
    Answer: The ratio is not fixed
  29. An emulsifier with an HLB value of 12 would be:
    • Lipophilic
    • Hydrophilic
    • Equally lipophilic and hydrophilic
    • A solid
    Answer: Hydrophilic
  30. To increase the stability of an emulsion, one can:
    • Increase the globule size
    • Decrease the viscosity of the external phase
    • Increase the viscosity of the external phase
    • Use an emulsifier with an incorrect HLB value
    Answer: Increase the viscosity of the external phase
  31. Milk is a natural ______ emulsion.
    • w/o
    • o/w
    • w/o/w
    • o/w/o
    Answer: o/w
  32. A filter paper test can be used to identify emulsion type. If a drop of emulsion spreads rapidly on a filter paper, it is likely a(n):
    • o/w emulsion
    • w/o emulsion
    • Unstable emulsion
    • Suspension
    Answer: o/w emulsion
  33. The size of the dispersed globules in a pharmaceutical emulsion is typically in the range of:
    • 1-5 nanometers
    • 0.1-100 micrometers
    • 1 millimeter
    • < 0.1 micrometers
    Answer: 0.1-100 micrometers
  34. Which of the following would NOT be considered an emulsifying agent?
    • Acacia
    • Sucrose
    • Gelatin
    • Tween 80
    Answer: Sucrose
  35. The external phase of an emulsion is also known as the:
    • Dispersion medium
    • Dispersed phase
    • Internal phase
    • Globule
    Answer: Dispersion medium
  36. Coalescence is the direct cause of which instability phenomenon?
    • Creaming
    • Sedimentation
    • Breaking
    • Flocculation
    Answer: Breaking
  37. In the English method, the primary emulsion is formed by triturating:
    • Gum with oil first, then adding water.
    • Gum with water first, then adding oil slowly.
    • Oil with water first, then adding gum.
    • All components together at once.
    Answer: Gum with water first, then adding oil slowly.
  38. “Spans” are emulsifying agents that are generally:
    • Hydrophilic
    • Lipophilic
    • Water-soluble
    • High HLB
    Answer: Lipophilic
  39. The most thermodynamically stable type of emulsion is a(n):
    • Macroemulsion
    • Microemulsion
    • w/o emulsion
    • o/w emulsion
    Answer: Microemulsion
  40. An emulsion for intravenous administration must be a(n):
    • w/o type
    • o/w type
    • Multiple emulsion
    • Any type is acceptable
    Answer: o/w type
  41. Which statement is true about creaming?
    • It is a sign of irreversible instability.
    • It can be reduced by increasing the globule size.
    • It can be corrected by gentle shaking.
    • It is the complete separation of the two phases.
    Answer: It can be corrected by gentle shaking.
  42. The “crackling” sound heard when mixing oil and water with gum in the dry gum method indicates:
    • The emulsion is breaking.
    • The primary emulsion is forming.
    • The gum is not soluble.
    • The oil is rancid.
    Answer: The primary emulsion is forming.
  43. A key advantage of emulsions as a dosage form is the ability to:
    • Administer oily drugs in a more palatable form.
    • Ensure perfect physical stability.
    • Avoid using excipients.
    • Deliver drugs as a single phase.
    Answer: Administer oily drugs in a more palatable form.
  44. “Tweens” are emulsifying agents that are generally:
    • Lipophilic
    • Hydrophilic
    • Oil-soluble
    • Low HLB
    Answer: Hydrophilic
  45. What is the main difference between an emulsion and a microemulsion?
    • An emulsion is a single phase.
    • A microemulsion is thermodynamically stable and has a much smaller globule size.
    • A microemulsion is always a w/o type.
    • An emulsion does not require an emulsifier.
    Answer: A microemulsion is thermodynamically stable and has a much smaller globule size.
  46. In the continental method, the initial mixture of oil, water, and gum is called the:
    • Secondary emulsion
    • Continuous phase
    • Primary emulsion or nucleus
    • Dispersed phase
    Answer: Primary emulsion or nucleus
  47. To make a stable w/o emulsion, the emulsifying agent should have an HLB value in the range of:
    • 1-3
    • 3-6
    • 8-18
    • 13-15
    Answer: 3-6
  48. Which of the following factors does NOT significantly affect the stability of an emulsion?
    • Globule size
    • Viscosity of the external phase
    • The density difference between the two phases
    • The color of the external phase
    Answer: The color of the external phase
  49. A key physical characteristic of a good emulsion is:
    • Rapid separation into two layers
    • A uniform, homogenous appearance
    • Large visible droplets
    • A gritty texture
    Answer: A uniform, homogenous appearance
  50. The term “biphasic” refers to the presence of:
    • Two active drugs
    • Two distinct physical phases
    • Two preservatives
    • Two different colors
    Answer: Two distinct physical phases

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