Surfactants used in herbal cosmetic formulations MCQs With Answer

Surfactants used in herbal cosmetic formulations MCQs With Answer

This quiz collection is designed for M.Pharm students studying Herbal Cosmetics (MPG 204T) and focuses on surfactants commonly used in herbal formulations. The set covers fundamental concepts—classification, mechanisms (CMC, HLB, micellization), and physicochemical properties—as well as practical formulation issues such as compatibility, irritation potential, biodegradability, and selection of natural surfactants (saponins, alkyl polyglucosides, lecithin). Questions emphasize analytical and stability tests, emulsification techniques (PIT, high-shear), and interactions with herbal actives. These MCQs are intended to deepen understanding beyond definitions by linking theory to formulation practice and regulatory/green considerations in herbal cosmetics.

Q1. What is the primary function of a surfactant in an oil‑in‑water herbal emulsion?

• Act as a preservative to inhibit microbial growth
• Reduce interfacial tension between immiscible phases
• Increase aqueous phase viscosity
• Act as a pH buffer

Correct Answer: Reduce interfacial tension between immiscible phases

Q2. Surfactants are conventionally classified according to the charge on their head group. Which of the following is NOT one of the four classical charge‑based classes?

• Anionic
• Cationic
• Nonionic
• Polymeric

Correct Answer: Polymeric

Q3. Which of the following is a plant‑derived natural surfactant frequently used in herbal cosmetics for foaming and emulsification?

• Sodium lauryl sulfate
• Quillaja saponins
• Polysorbate 20
• Cetyltrimethylammonium bromide

Correct Answer: Quillaja saponins

Q4. In the HLB system, emulsifiers with HLB values in which range are typically selected for oil‑in‑water (O/W) emulsions?

• 0–3
• 3–6
• 8–18
• > 20

Correct Answer: 8–18

Q5. What does the critical micelle concentration (CMC) represent for a surfactant solution?

• The concentration at which the surfactant decomposes
• The concentration at which micelles begin to form
• The maximum solubility of the surfactant
• The pH at which the surfactant ionizes

Correct Answer: The concentration at which micelles begin to form

Q6. Which class of surfactants is most commonly used as hair conditioning agents in cosmetic formulations?

• Anionic surfactants
• Cationic surfactants
• Nonionic surfactants
• Amphoteric surfactants

Correct Answer: Cationic surfactants

Q7. Among the following, which surfactant is generally considered least irritating and most suitable for mild herbal cleansers?

• Sodium lauryl sulfate
• Alkyl polyglucoside
• Cocamidopropyl betaine
• Benzalkonium chloride

Correct Answer: Alkyl polyglucoside

Q8. Which surfactant listed below also provides significant antimicrobial/preservative activity and is sometimes used in low concentrations for this purpose?

• Saponins
• Polysorbate 80
• Benzalkonium chloride
• Sorbitan monooleate

Correct Answer: Benzalkonium chloride

Q9. Which emulsification technique relies on changing temperature to temporarily alter surfactant solubility and invert the emulsion type?

• High shear homogenization
• Phase inversion temperature (PIT) method
• Microfluidization
• Ultrasonication

Correct Answer: Phase inversion temperature (PIT) method

Q10. What is the typical effect of adding an electrolyte (e.g., NaCl) to an aqueous solution of an ionic surfactant?

• Increase the CMC
• Decrease the CMC
• No effect on CMC
• Convert it irreversibly to a nonionic surfactant

Correct Answer: Decrease the CMC

Q11. Which measured parameter is most useful to predict colloidal stability of emulsion droplets by indicating the magnitude of surface charge?

• Viscosity
• Zeta potential
• pH
• Refractive index

Correct Answer: Zeta potential

Q12. Which surfactant class is produced by coupling a glucose (or polysaccharide) head group to a fatty alcohol and is favored in natural/green formulations?

• Polysorbates
• Alkyl polyglucoside
• Sodium lauryl sulfate
• Cocamide DEA

Correct Answer: Alkyl polyglucoside

Q13. Cocamidopropyl betaine is categorized as which type of surfactant?

• Anionic
• Cationic
• Amphoteric (zwitterionic)
• Nonionic

Correct Answer: Amphoteric (zwitterionic)

Q14. In herbal cosmetics, saponins derived from plants (e.g., soapnut, quillaja) are primarily utilized for which formulation functions?

• Preservative action
• Foaming and wetting agents
• Fragrance delivery
• Color stabilization

Correct Answer: Foaming and wetting agents

Q15. How does increasing the hydrophobic alkyl chain length of a surfactant generally affect its critical micelle concentration (CMC)?

• CMC increases
• CMC decreases
• CMC remains unchanged
• CMC becomes infinite

Correct Answer: CMC decreases

Q16. Which surfactant is most often cited as biodegradable and suitable for eco‑friendly herbal cosmetic formulations?

• Sodium lauryl sulfate
• Alkyl polyglucoside
• Polysorbate 80
• Cetyltrimethylammonium bromide

Correct Answer: Alkyl polyglucoside

Q17. Which analytical technique is classically used to determine the CMC by observing the break point in surface tension versus concentration?

• Conductivity measurement
• Tensiometry (surface tension measurement)
• Differential scanning calorimetry (DSC)
• FTIR spectroscopy

Correct Answer: Tensiometry (surface tension measurement)

Q18. Mixing which two surfactant types frequently leads to precipitation or loss of performance due to insoluble ion pair formation?

• Anionic + cationic
• Nonionic + cationic
• Amphoteric + nonionic
• All surfactant combinations are always compatible

Correct Answer: Anionic + cationic

Q19. For solubilizing essential oils and lipophilic herbal actives into aqueous systems, which surfactant is commonly used as a solubilizer/emulsifier?

• Polysorbate 80 (Tween 80)
• Sodium lauryl sulfate
• Cetylpyridinium chloride
• Sorbitan monooleate (Span 80)

Correct Answer: Polysorbate 80 (Tween 80)

Q20. What does the Krafft temperature describe for ionic surfactants used in cosmetic formulations?

• The temperature at which an emulsion inverts from O/W to W/O
• The temperature below which ionic surfactant solubility is insufficient to form micelles
• The melting point of the surfactant molecule
• The temperature at which the HLB value changes

Correct Answer: The temperature below which ionic surfactant solubility is insufficient to form micelles

Download