Detergency MCQs With Answer

Detergency MCQs With Answer is an essential resource for B. Pharm students aiming to master surfactant science, cleaning mechanisms, and formulation implications in pharmaceuticals. This concise, keyword-rich introduction covers detergency fundamentals such as surfactant types, critical micelle concentration (CMC), wetting, emulsification, foaming, builders, enzymes, and environmental biodegradability. Emphasis is placed on how detergents interact with drug excipients, influence solubilization, and affect stability and drug delivery systems. Questions focus on practical testing methods, formulation strategies, and regulatory considerations relevant to pharmaceutical cleaning and product design. Clear answers help reinforce learning and exam readiness. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the fundamental mechanism by which surfactants promote detergency?

• Denaturation of proteins on surfaces
• Increase in solution viscosity
• Reduction of surface and interfacial tension
• Neutralization of ionic contaminants

Correct Answer: Reduction of surface and interfacial tension

Q2. Which parameter defines the concentration above which micelles form in a surfactant solution?

• Hydrophilic–lipophilic balance (HLB)
• Critical micelle concentration (CMC)
• Cloud point
• Isoelectric point

Correct Answer: Critical micelle concentration (CMC)

Q3. Which surfactant type carries no net electrical charge on its head group?

• Anionic
• Cationic
• Nonionic
• Zwitterionic

Correct Answer: Nonionic

Q4. In pharmaceutical cleaning validation, which property of a detergent is most critical for removing proteinaceous residues?

• Foaming capacity
• Enzymatic activity or inclusion
• Color stability
• Low pH

Correct Answer: Enzymatic activity or inclusion

Q5. A high HLB value indicates a surfactant is more:

• Oil-soluble and lipophilic
• Balanced equally oil and water soluble
• Water-soluble and hydrophilic
• Unstable in aqueous solution

Correct Answer: Water-soluble and hydrophilic

Q6. Which surfactant class is commonly used as antimicrobial preservatives in formulations?

• Anionic surfactants
• Cationic surfactants (e.g., quaternary ammonium compounds)
• Nonionic surfactants
• Amphoteric surfactants

Correct Answer: Cationic surfactants (e.g., quaternary ammonium compounds)

Q7. Which factor does NOT generally improve detergency performance?

• Appropriate surfactant selection
• Optimized temperature
• Presence of appropriate builders
• Lowering solution pH to extremely acidic levels for all soils

Correct Answer: Lowering solution pH to extremely acidic levels for all soils

Q8. What role do builders play in detergent formulations?

• Act as primary surfactants
• Enhance soil suspension and soften water by chelating hardness ions
• Increase foaming only
• Act as preservatives

Correct Answer: Enhance soil suspension and soften water by chelating hardness ions

Q9. Which test measures a detergent’s ability to reduce surface tension?

• Cloud point determination
• Surface tension measurement (e.g., tensiometry)
• Foam height test only
• Viscosity profiling

Correct Answer: Surface tension measurement (e.g., tensiometry)

Q10. In detergency, what is the significance of the cloud point for nonionic surfactants?

• It indicates temperature where surfactant degrades
• It marks the temperature above which the surfactant becomes less soluble and separates
• It is the pH where micelles form
• It indicates maximum foaming temperature

Correct Answer: It marks the temperature above which the surfactant becomes less soluble and separates

Q11. Which surfactant is likely to be least irritating to skin and mucous membranes?

• Strong anionic surfactants like SDS
• Cationic quaternary ammonium compounds
• Mild nonionic surfactants like polysorbates
• Unsulfated alkylbenzene sulfonates

Correct Answer: Mild nonionic surfactants like polysorbates

Q12. Why is CMC important in drug solubilization using surfactants?

• Below CMC, micelles solubilize drugs efficiently
• Above CMC, micelles form and can solubilize lipophilic drugs
• CMC determines the pH of the solution
• CMC prevents protein denaturation

Correct Answer: Above CMC, micelles form and can solubilize lipophilic drugs

Q13. Which method is commonly used to determine foaming properties of detergents?

• Cloud point test
• Ross-Miles foam test
• Viscometry
• Infrared spectroscopy

Correct Answer: Ross-Miles foam test

Q14. Which statement best describes zeolites in detergent formulations?

• They are surfactants that increase foaming
• They are builders used to replace phosphates and soften water
• They are enzymes that break down proteins
• They are fragrances to mask odors

Correct Answer: They are builders used to replace phosphates and soften water

Q15. How do enzymes improve detergency in laundry or formulation cleaning?

• They act as surfactants to reduce surface tension
• They catalyze the breakdown of specific soils like proteins, starches, and fats
• They increase the density of the solution
• They bind to heavy metals in water

Correct Answer: They catalyze the breakdown of specific soils like proteins, starches, and fats

Q16. Which ionic strength effect commonly influences surfactant behavior in solution?

• High ionic strength decreases micelle formation for all surfactants
• Ionic strength can screen electrostatic repulsions, affecting CMC and micelle size for ionic surfactants
• Ionic strength converts nonionic surfactants to ionic ones
• Ionic strength has no effect on detergency

Correct Answer: Ionic strength can screen electrostatic repulsions, affecting CMC and micelle size for ionic surfactants

Q17. Which is a common anionic surfactant used in many detergent formulations?

• Polysorbate 80
• Sodium lauryl sulfate (SLS)
• Cetyltrimethylammonium bromide
• Lauryl glucoside

Correct Answer: Sodium lauryl sulfate (SLS)

Q18. What is the likely effect of hard water on anionic surfactant performance?

• Hard water enhances anionic surfactant efficiency
• Calcium and magnesium ions form insoluble soaps, reducing detergency
• Hard water converts anionic surfactants into enzymes
• No effect on surfactant performance

Correct Answer: Calcium and magnesium ions form insoluble soaps, reducing detergency

Q19. Which metric is used to quantify soil removal efficiency in cleaning studies?

• pKa
• Soil removal percentage or detergency index
• Boiling point elevation
• Optical rotation

Correct Answer: Soil removal percentage or detergency index

Q20. In pharmaceutical manufacturing, why is validation of cleaning processes with detergents necessary?

• To ensure equipment color matches product packaging
• To demonstrate reproducible removal of cross-contaminants and residues to acceptable limits
• To increase foaming in cleaning cycles
• To reduce manufacturing time irrespective of cleanliness

Correct Answer: To demonstrate reproducible removal of cross-contaminants and residues to acceptable limits

Q21. Which surfactant property influences wetting ability on solid pharmaceutical surfaces?

• Cloud point only
• Ability to lower surface tension and contact angle
• Viscosity at high shear
• Oxidation potential

Correct Answer: Ability to lower surface tension and contact angle

Q22. What is a primary environmental concern with certain traditional detergent builders like phosphates?

• They cause corrosion of stainless steel
• They contribute to eutrophication in aquatic systems
• They reduce surfactant biodegradation
• They increase formulation viscosity excessively

Correct Answer: They contribute to eutrophication in aquatic systems

Q23. Which surfactant type is amphoteric and can change charge with pH?

• Anionic surfactants
• Cationic surfactants
• Amphoteric (zwitterionic) surfactants
• Nonionic surfactants

Correct Answer: Amphoteric (zwitterionic) surfactants

Q24. For solubilization of lipophilic drugs in aqueous media, which surfactant characteristic is most desirable?

• Extremely high CMC
• Ability to form micelles with hydrophobic cores above CMC
• Strong acidity
• High foaming tendency only

Correct Answer: Ability to form micelles with hydrophobic cores above CMC

Q25. Which analytical technique can quantify residual detergent on pharmaceutical equipment?

• Gravimetric analysis only
• High-performance liquid chromatography (HPLC) or colorimetric assays
• NMR that ignores surfactant signals
• Simple pH measurement

Correct Answer: High-performance liquid chromatography (HPLC) or colorimetric assays

Q26. What effect do surfactants have on permeability of lipid membranes relevant to drug delivery?

• They always stiffen membranes and reduce permeability
• They can fluidize membranes and increase permeability, depending on type and concentration
• They convert membranes into crystalline solids
• No interaction with membranes at any concentration

Correct Answer: They can fluidize membranes and increase permeability, depending on type and concentration

Q27. Which factor is crucial when choosing a detergent for cleaning pharmaceutical glassware?

• Color of detergent
• Compatibility with glass and absence of residues that interfere with assays
• High fragrance content
• Ability to stain glass for easy identification

Correct Answer: Compatibility with glass and absence of residues that interfere with assays

Q28. In surfactant mixtures, what is a common benefit of combining anionic and nonionic surfactants?

• Always reduces cleaning power
• Combines strong wetting and solubilization with lower irritation and better stability
• Produces a single-phase solid
• Eliminates micelle formation

Correct Answer: Combines strong wetting and solubilization with lower irritation and better stability

Q29. Which property of a detergent influences its ability to remove oily or greasy soils?

• Hydrophilic–lipophilic balance (HLB) favoring lipophilic interaction
• Low molecular weight only
• Strong acidity exclusively
• High color intensity

Correct Answer: Hydrophilic–lipophilic balance (HLB) favoring lipophilic interaction

Q30. Which surfactant parameter often decreases with increasing alkyl chain length?

• Hydrophobicity
• CMC
• Ability to form micelles
• Binding to oils

Correct Answer: CMC

Q31. Which is a biodegradable surfactant class preferred for environmental safety?

• Linear alkylbenzene sulfonates (LAS) and alkyl ethoxylates
• Highly branched alkylbenzene sulfonates only
• Heavy metal-containing surfactants
• Perfluorinated surfactants

Correct Answer: Linear alkylbenzene sulfonates (LAS) and alkyl ethoxylates

Q32. What is the expected effect of adding salts like NaCl to a solution of ionic surfactant?

• Increase electrostatic repulsion
• Screen charges, often decreasing CMC and promoting micelle growth
• Convert ionic surfactant to nonionic
• Prevent micelle formation entirely

Correct Answer: Screen charges, often decreasing CMC and promoting micelle growth

Q33. In detergency, what is meant by ‘soil redeposition’?

• Permanent removal of soils into wastewater
• Removal of soil from one area and its reattachment elsewhere during washing
• Chemical degradation of soil to harmless products
• Evaporation of soil components

Correct Answer: Removal of soil from one area and its reattachment elsewhere during washing

Q34. Which enzyme is most effective against proteinaceous stains in detergents?

• Amylase
• Protease
• Lipase
• Cellulase

Correct Answer: Protease

Q35. Which surfactant can act as a penetration enhancer in transdermal formulations?

• Sodium chloride
• Certain nonionic surfactants like polysorbates or fatty acid esters
• Phosphate builders
• Inert glass beads

Correct Answer: Certain nonionic surfactants like polysorbates or fatty acid esters

Q36. What does the term ‘micelle solubilization capacity’ refer to?

• The number of micelles per liter
• The maximum amount of hydrophobic solute micelles can incorporate
• The ability of micelles to generate foam
• The micelle’s electrical conductivity

Correct Answer: The maximum amount of hydrophobic solute micelles can incorporate

Q37. Which method assesses surface cleanliness by measuring organic carbon residues?

• TOC (Total Organic Carbon) analysis
• pH strip test
• Conductivity alone
• Refractometry

Correct Answer: TOC (Total Organic Carbon) analysis

Q38. How does temperature generally affect detergency efficiency?

• Higher temperature always decreases detergency
• Increasing temperature often improves solubility and reaction rates, enhancing detergency up to a limit
• Temperature has no effect on detergency
• Only cold temperatures solubilize oils

Correct Answer: Increasing temperature often improves solubility and reaction rates, enhancing detergency up to a limit

Q39. Which additive stabilizes enzymes in detergent formulations?

• Bleach only
• Polyols and calcium chelators or stabilizers
• Strong acids
• Heavy metals like mercury

Correct Answer: Polyols and calcium chelators or stabilizers

Q40. In cleaning-in-place (CIP) systems, what characteristic is essential for detergents?

• High foaming to indicate flow
• Low residue formation and effective rinseability
• Bright color to indicate presence
• High viscosity to cling to surfaces

Correct Answer: Low residue formation and effective rinseability

Q41. Which of the following is a common test soil used in detergency studies to simulate fatty soils?

• Proteinaceous egg albumin only
• Standardized oily soils like SAE 40 oil or mixed fatty soils
• Pure sodium chloride crystals
• Cellulose powder alone

Correct Answer: Standardized oily soils like SAE 40 oil or mixed fatty soils

Q42. Why might a B. Pharm student study detergency in relation to tablet manufacturing?

• Detergency has no relevance to tablet production
• Surfactants and cleaning agents can affect tablet coating, residue control, and cross-contamination risk
• To learn how to make tablets foam
• To replace binders with detergents

Correct Answer: Surfactants and cleaning agents can affect tablet coating, residue control, and cross-contamination risk

Q43. Which surfactant feature reduces irritation while maintaining detergency for topical formulations?

• High concentration of strong anionic surfactants
• Use of mild nonionic or amphoteric surfactants at optimized concentrations
• Inclusion of heavy metals
• Extremely low pH

Correct Answer: Use of mild nonionic or amphoteric surfactants at optimized concentrations

Q44. What is the likely impact of residual detergents on analytical assays if not removed from glassware?

• No impact on any assay
• They may interfere with assays by causing surface tension changes, adsorption, or chemical reaction with analytes
• They only affect colorimetric tests but nothing else
• They increase assay speed without interference

Correct Answer: They may interfere with assays by causing surface tension changes, adsorption, or chemical reaction with analytes

Q45. Which surfactant would be preferred for ophthalmic formulations due to low irritation and compatibility?

• Strong anionic surfactants like SLS
• Mild nonionic surfactants such as polysorbates at low concentrations
• Cationic antiseptics only
• Industrial degreasers

Correct Answer: Mild nonionic surfactants such as polysorbates at low concentrations

Q46. What is the effect of increasing surfactant concentration far above the CMC on micelle population?

• Micelle population and size can increase, but incremental solubilization may plateau
• Micelles disappear
• Surfactant becomes completely inactive
• No change after CMC is reached

Correct Answer: Micelle population and size can increase, but incremental solubilization may plateau

Q47. Which component in detergents acts to prevent scale formation by sequestering metal ions?

• Fragrance
• Sequestering agents such as EDTA or citrate
• Brighteners
• Colorants

Correct Answer: Sequestering agents such as EDTA or citrate

Q48. What is a potential drawback of excessive foaming in industrial cleaning?

• Improved cleaning efficiency always
• Foam can hinder rinse and circulation, requiring antifoaming measures
• Foam sterilizes surfaces
• Foam increases sequestering efficiency

Correct Answer: Foam can hinder rinse and circulation, requiring antifoaming measures

Q49. Which additive is used to improve whitening or optical appearance in detergents?

• Optical brighteners (fluorescent whitening agents)
• Strong acids
• Heavy metal salts
• Enzyme inhibitors

Correct Answer: Optical brighteners (fluorescent whitening agents)

Q50. In the context of pharmaceutical detergency, what is the significance of biodegradability testing?

• It determines cleaning speed only
• It assesses environmental impact and regulatory compliance for disposal of detergent-containing waste
• It measures viscosity of detergent solutions
• It evaluates taste masking properties

Correct Answer: It assesses environmental impact and regulatory compliance for disposal of detergent-containing waste

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com