Vanishing cream formulation MCQs With Answer

Vanishing cream formulation MCQs With Answer

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Vanishing cream formulation MCQs With Answer

Introduction

This set of MCQs on vanishing cream formulation has been created for M.Pharm students studying Cosmetics & Cosmeceuticals (MPH 204T). The quiz covers formulation principles, common excipients, emulsification chemistry, processing parameters, stability testing, evaluation methods and troubleshooting specific to vanishing creams. Questions range from basic definitions to formulation optimization, analytical tests and compatibility issues faced during development. These items are intended to deepen understanding of how oil-in-water vanishing creams are designed to “vanish” on the skin, the role of stearic acid/neutralization systems, HLB concepts, rheology control and preservative selection—helpful for both exam preparation and practical formulation design.

Q1. Which emulsion type is a classical vanishing cream formulation?

  • Water-in-oil (W/O)
  • Oil-in-water (O/W)
  • Multiple emulsion (W/O/W)
  • Anhydrous gel

Correct Answer: Oil-in-water (O/W)

Q2. Which combination is most commonly used to form the primary emulsifier in traditional vanishing creams?

  • Stearic acid neutralized with triethanolamine
  • Glyceryl monostearate with sodium lauryl sulfate
  • Polysorbate 80 with cetyl alcohol
  • Lanolin with borax

Correct Answer: Stearic acid neutralized with triethanolamine

Q3. The neutralization of stearic acid by triethanolamine produces which functional species acting as emulsifier?

  • Nonionic surfactant
  • Cationic surfactant
  • Anionic soap (triethanolamine stearate)
  • Zwitterionic surfactant

Correct Answer: Anionic soap (triethanolamine stearate)

Q4. Which HLB range is most appropriate for surfactants used to form stable oil-in-water emulsions like vanishing creams?

  • 1–3
  • 4–6
  • 8–18
  • 20–25

Correct Answer: 8–18

Q5. What is the primary reason a vanishing cream appears to “vanish” after application?

  • Rapid chemical decomposition of oils into gases
  • Evaporation of water followed by formation of a thin stearate film and spread of oil phase
  • Complete penetration of all constituents into dermis within seconds
  • Phase inversion to anhydrous solid

Correct Answer: Evaporation of water followed by formation of a thin stearate film and spread of oil phase

Q6. Which ingredient is commonly added as a humectant in vanishing cream formulations?

  • Glycerin
  • Mineral oil
  • Stearic acid
  • Beeswax

Correct Answer: Glycerin

Q7. During manufacture of a vanishing cream, the typical emulsification temperature (for both aqueous and oil phases) is usually around:

  • 30–40°C
  • 50–60°C
  • 70–80°C
  • 90–100°C

Correct Answer: 70–80°C

Q8. Which excipient is commonly used to increase viscosity and improve skin feel in vanishing creams?

  • Cetyl/stearyl alcohol
  • Sodium lauryl sulfate
  • Isopropyl myristate (only)
  • Hydrogen peroxide

Correct Answer: Cetyl/stearyl alcohol

Q9. Which analytical test best distinguishes O/W from W/O emulsion for vanishing cream?

  • Conductivity test and water-soluble dye test
  • pH measurement only
  • Infrared spectroscopy
  • Melting point determination

Correct Answer: Conductivity test and water-soluble dye test

Q10. Which preservative class is generally incompatible with anionic emulsifiers like TEA stearate and should be avoided or used carefully?

  • Non-ionic parabens
  • Phenoxyethanol
  • Cationic preservatives (e.g., benzalkonium chloride)
  • Organic acids (e.g., sorbic acid)

Correct Answer: Cationic preservatives (e.g., benzalkonium chloride)

Q11. What rheological behavior is desirable for vanishing creams to ensure good spreadability and consumer acceptance?

  • Newtonian, constant viscosity
  • Pseudoplastic (shear-thinning) with moderate thixotropy
  • Dilatant (shear-thickening)
  • Bingham plastic with very high yield stress

Correct Answer: Pseudoplastic (shear-thinning) with moderate thixotropy

Q12. Which stability test is most useful for early detection of physical instability like coalescence or phase separation in a vanishing cream?

  • Centrifugation and freeze–thaw cycling
  • UV spectroscopy at 260 nm
  • HPLC for preservative content only
  • Microbial limit test only

Correct Answer: Centrifugation and freeze–thaw cycling

Q13. If a vanishing cream formulation shows gradual increase in pH on storage, what is the most likely chemical cause?

  • Hydrolysis of glycerin to acidic products
  • Generation of free fatty acids from oil oxidation
  • Migration or loss of free acid leading to increased formation of soap by neutralizer depletion
  • Absorption of CO2 from air making it more alkaline

Correct Answer: Migration or loss of free acid leading to increased formation of soap by neutralizer depletion

Q14. Which oil is commonly used in vanishing creams for non-greasy feel?

  • Mineral oil (light paraffinic fractions)
  • Coconut oil (solid at room temperature)
  • Olive oil (very heavy)
  • Castor oil (very viscous)

Correct Answer: Mineral oil (light paraffinic fractions)

Q15. For formulation robustness, what is the primary effect of increasing cetyl alcohol concentration in a vanishing cream?

  • Decrease viscosity and increase runniness
  • Increase viscosity, improve emulsion stability and enhance skin feel
  • Create a water-in-oil emulsion exclusively
  • Act as a preservative

Correct Answer: Increase viscosity, improve emulsion stability and enhance skin feel

Q16. Which microstructure parameter must be minimized to ensure the cream “vanishes” without leaving a white residue?

  • Large oil globule size (>10 µm)
  • pH below 3
  • High glycerin concentration
  • Low emulsifier content

Correct Answer: Large oil globule size (>10 µm)

Q17. Which method of emulsification is most effective to reduce globule size and produce a smooth vanishing cream?

  • Slow hand stirring at ambient temperature
  • High-shear homogenization at emulsification temperature
  • Dry blending in a paddle mixer without heating
  • Freeze mixing

Correct Answer: High-shear homogenization at emulsification temperature

Q18. Which preservative system is typically compatible and effective in vanishing creams containing triethanolamine stearate?

  • Parabens (methyl/propyl paraben) or phenoxyethanol
  • Cationic quaternary ammonium compounds only
  • Strongly alkaline preservatives (pH > 12)
  • Unbuffered sodium hypochlorite

Correct Answer: Parabens (methyl/propyl paraben) or phenoxyethanol

Q19. Which parameter is most critical to control to prevent rancidity and off-odors in vanishing cream formulations containing fatty materials?

  • Water activity and antioxidant addition
  • Increasing emulsifier HLB only
  • Raising formulation pH above 10
  • Adding more mineral oil

Correct Answer: Water activity and antioxidant addition

Q20. In accelerated stability studies for vanishing cream, which observation most strongly indicates ongoing chemical incompatibility between components?

  • Minor reversible change in spreadability
  • Significant color change, phase separation and pH drift
  • Temporary cooling-induced viscosity increase that reverses on warming
  • Unchanged viscosity with only slight fragrance loss

Correct Answer: Significant color change, phase separation and pH drift

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