Uses of paraffins MCQs With Answer is an essential topic for B.Pharm students studying pharmaceutical excipients and topical/oral formulations. This introduction covers paraffin types—white soft paraffin, liquid paraffin (mineral oil), paraffin wax and microcrystalline wax—their physicochemical properties, pharmaceutical applications as ointment bases, emollients, lubricants, tablet coatings and laxatives, plus safety and quality control tests. Understanding melting point, solubility, chemical inertness and toxicity (aspiration risk, interference with fat‑soluble vitamin absorption) helps in rational formulation design. Keywords: paraffins, liquid paraffin, white soft paraffin, paraffin wax, ointment base, pharmaceutical excipient. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the primary chemical nature of paraffins used in pharmaceutical excipients?
- Saturated hydrocarbons
- Unsaturated fatty acids
- Polysaccharides
- Polymeric esters
Correct Answer: Saturated hydrocarbons
Q2. Which paraffin product is commonly used as an occlusive ointment base in topical formulations?
- Liquid paraffin
- White soft paraffin (petrolatum)
- Microcrystalline wax
- Beeswax
Correct Answer: White soft paraffin (petrolatum)
Q3. Liquid paraffin in pharmacy is often synonymous with which term?
- Mineral oil
- Polydimethylsiloxane
- Isopropyl myristate
- Lanolin
Correct Answer: Mineral oil
Q4. Which property makes paraffin wax useful for tablet coating and controlled release layers?
- Hydrophilicity
- High melting point and hydrophobicity
- High acidity
- Enzymatic degradability
Correct Answer: High melting point and hydrophobicity
Q5. Microcrystalline wax differs from paraffin wax mainly by having:
- Lower molecular weight and larger crystals
- Higher branching and smaller crystals
- Higher unsaturation
- Polysaccharide chains
Correct Answer: Higher branching and smaller crystals
Q6. Which paraffin excipient is most suitable as an emollient in creams to reduce transepidermal water loss?
- White soft paraffin
- Glycerol
- Sodium lauryl sulfate
- Ethyl alcohol
Correct Answer: White soft paraffin
Q7. Major safety concern when using oral liquid paraffin as a laxative is:
- Renal toxicity
- Aspiration pneumonia
- Severe hyponatremia
- Hepatotoxicity
Correct Answer: Aspiration pneumonia
Q8. Which pharmacopoeial test is commonly used to characterize paraffin wax softening behavior?
- Iodine value
- Drop melting point
- Saponification value
- Acid value
Correct Answer: Drop melting point
Q9. Why do paraffins have very low iodine values in analytical tests?
- They are highly saturated hydrocarbons with minimal unsaturation
- They contain many esters
- They are highly oxidized
- They contain aromatic rings
Correct Answer: They are highly saturated hydrocarbons with minimal unsaturation
Q10. White soft paraffin is mainly used in ointments because it is:
- Highly volatile
- Hydrophilic and greaseless
- Stable, inert and occlusive
- Strongly acidic
Correct Answer: Stable, inert and occlusive
Q11. Which effect of long-term oral mineral oil use is of clinical significance?
- Increased absorption of fat‑soluble vitamins
- Interference with absorption of fat‑soluble vitamins
- Potent diuretic effect
- Enhanced protein absorption
Correct Answer: Interference with absorption of fat‑soluble vitamins
Q12. The main reason paraffins are resistant to oxidation is that they:
- Have saturated C–H bonds without double bonds
- Contain many hydroxyl groups
- Are rich in conjugated double bonds
- Contain peroxy linkages
Correct Answer: Have saturated C–H bonds without double bonds
Q13. Which paraffin excipient is commonly used to stiffen ointment bases and increase melting point?
- Liquid paraffin
- Paraffin wax
- Glycerin
- Propylene glycol
Correct Answer: Paraffin wax
Q14. In ointment formulation, white soft paraffin acts primarily as a:
- Humectant
- Oleaginous base
- Surfactant
- Preservative
Correct Answer: Oleaginous base
Q15. Which analytical technique is most useful to determine the hydrocarbon composition and molecular weight distribution of paraffins?
- UV-Vis spectroscopy
- Gas chromatography (GC)
- Titration with NaOH
- Polarimetry
Correct Answer: Gas chromatography (GC)
Q16. Compared to paraffin wax, microcrystalline wax typically exhibits:
- Lower viscosity and larger crystals
- Higher viscosity and finer crystals
- High degree of unsaturation
- High water solubility
Correct Answer: Higher viscosity and finer crystals
Q17. Which parameter is not applicable to pure paraffins because they contain no ester groups?
- Acid value
- Saponification value
- Melting point
- Refractive index
Correct Answer: Saponification value
Q18. A common topical formulation using white soft paraffin and liquid paraffin in combination is called:
- Hydrophilic ointment
- Yellow ointment
- Simple ointment (e.g., unguentum simplex)
- Water‑in‑oil cream
Correct Answer: Simple ointment (e.g., unguentum simplex)
Q19. Which of the following is an advantage of paraffins as pharmaceutical excipients?
- High chemical reactivity improves drug release
- Biodegradable enzymatic breakdown in skin
- Low reactivity and good chemical stability
- Strong antimicrobial activity
Correct Answer: Low reactivity and good chemical stability
Q20. Which test would best indicate the presence of unsaturated contaminants in a paraffin sample?
- Measurement of melting point alone
- Iodine value determination
- Determination of density only
Correct Answer: Iodine value determination
Q21. In compounding, white soft paraffin is often used to prepare medicated creams because it:
- Attracts moisture from the air (humectant)
- Forms an occlusive barrier and stabilizes formulations
- Rapidly evaporates leaving the drug on skin
- Acts as an emulsifying agent
Correct Answer: Forms an occlusive barrier and stabilizes formulations
Q22. Which is true about the solubility of paraffins?
- They are miscible with water
- They are soluble in nonpolar organic solvents like hexane
- They dissolve readily in ethanol
- They form hydrogen bonds with glycerin
Correct Answer: They are soluble in nonpolar organic solvents like hexane
Q23. Which paraffin grade is typically used in pharmaceutical ointments to avoid skin staining and irritation?
- Crude paraffin oil
- Technical paraffin wax
- White, purified paraffin (pharmaceutical grade)
- Unrefined mineral oil
Correct Answer: White, purified paraffin (pharmaceutical grade)
Q24. Which of the following is NOT a pharmaceutical application of paraffins?
- Ointment base
- Tablet lubricant/coating
- Antibiotic active ingredient
- Laxative (mineral oil)
Correct Answer: Antibiotic active ingredient
Q25. The term ‘white soft paraffin’ in pharmacopeias generally corresponds to which substance?
- Petrolatum (white petrolatum)
- Liquid paraffin (mineral oil)
- Microcrystalline wax
- Polyethylene glycol
Correct Answer: Petrolatum (white petrolatum)
Q26. For quality control, which physical test distinguishes microcrystalline wax from paraffin wax?
- Iodine value only
- Crystal structure under microscopy and needle penetration
- Saponification test
- pH measurement
Correct Answer: Crystal structure under microscopy and needle penetration
Q27. Which paraffin property is most critical when designing a topical formulation intended to melt at body temperature?
- Acid value
- Melting point / softening point
- Density
- Optical rotation
Correct Answer: Melting point / softening point
Q28. Which paraffin derivative is contraindicated in children due to high aspiration risk when used orally?
- Edible vegetable oil
- Mineral oil (liquid paraffin)
- Glycerol suppositories
- Polyethylene glycol solution
Correct Answer: Mineral oil (liquid paraffin)
Q29. Paraffins are chemically inert because they lack which functional group?
- Alkane C–H bonds
- Carbonyl groups
- Saturated hydrocarbon chains
- Aromatic rings
Correct Answer: Carbonyl groups
Q30. Which method is commonly used to purify paraffinic oils for pharmaceutical use?
- Simple filtration through cotton
- Fractional distillation and refining
- Acid hydrolysis
- Saponification followed by salting out
Correct Answer: Fractional distillation and refining
Q31. In topical dermatological therapy, white soft paraffin promotes healing mainly by:
- Acting as an antiseptic
- Providing an occlusive barrier that enhances hydration
- Stimulating local blood flow via vasodilation
- Penetrating deeply into systemic circulation
Correct Answer: Providing an occlusive barrier that enhances hydration
Q32. Which measurement differentiates liquid paraffin grades for oral medicinal use?
- Viscosity and degree of refinement
- pH value
- Protein content
- Carbohydrate profile
Correct Answer: Viscosity and degree of refinement
Q33. Which excipient combination is often used to produce a soft, spreadable ointment base?
- White soft paraffin and liquid paraffin
- Microcrystalline wax and silica gel
- Beeswax and sodium chloride
- Alcohol and talc
Correct Answer: White soft paraffin and liquid paraffin
Q34. When incorporating a lipophilic drug into a paraffin base, the drug release is generally:
- Enhanced due to rapid dissolution
- Reduced due to high hydrophobicity of the base
- Unaffected because paraffins are water soluble
- Instantaneous because paraffins are volatile
Correct Answer: Reduced due to high hydrophobicity of the base
Q35. Which environmental/handling precaution is important for paraffin wax during manufacturing?
- Avoid open flames; flammpable vapors and dust can ignite
- Store only at very high temperatures above 100°C
- Always mix with strong acids
- Ensure high humidity to prevent hardening
Correct Answer: Avoid open flames; flammpable vapors and dust can ignite
Q36. Which of the following is a correct statement about paraffins and microbiological growth?
- Paraffins support bacterial growth readily
- Due to hydrophobic and inert nature, paraffins have minimal nutrient value for microbes
- Paraffins are potent sterilants
- Paraffins catalyze microbial proliferation because of free fatty acids
Correct Answer: Due to hydrophobic and inert nature, paraffins have minimal nutrient value for microbes
Q37. Which test would detect the presence of aromatic hydrocarbons contamination in paraffin samples?
- GC-MS analysis
- Drop melting point only
- Visual observation of color only
- Saponification test
Correct Answer: GC-MS analysis
Q38. Which feature of paraffins makes them suitable as lubricants in capsule manufacture?
- High water solubility
- Low melting point and oily character to reduce friction
- Strong acidity to etch capsule surfaces
- High ionic conductivity
Correct Answer: Low melting point and oily character to reduce friction
Q39. Which statement about paraffin wax melting behavior is true?
- It shows a sharp single melting point like pure crystalline salts
- It often displays a melting range due to a mixture of hydrocarbons
- It decomposes before melting
- It sublimates directly from solid to gas at room temperature
Correct Answer: It often displays a melting range due to a mixture of hydrocarbons
Q40. In topical drug delivery, paraffins can enhance drug residence time on skin primarily by:
- Increasing transepidermal water loss
- Creating an occlusive film that slows wash-off
- Acting as a penetration enhancer that increases systemic absorption dramatically
- Promoting rapid evaporation
Correct Answer: Creating an occlusive film that slows wash-off
Q41. Which adverse interaction may occur if mineral oil is taken with certain oral medications?
- Increased absorption of fat‑soluble drugs
- Reduced absorption of concurrently administered fat‑soluble drugs
- Complete chemical neutralization of other drugs
- Formation of insoluble salts in the stomach
Correct Answer: Reduced absorption of concurrently administered fat‑soluble drugs
Q42. What is a common method to incorporate a drug into a paraffin wax matrix for sustained release?
- Solvent evaporation and fusion (melt) method
- Simple aqueous dissolution
- Immediate lyophilization
- Electrolytic deposition
Correct Answer: Solvent evaporation and fusion (melt) method
Q43. Which paraffin fraction is typically solid at room temperature and used for candle making and stiffening?
- Liquid paraffin
- Paraffin wax
- Volatile oil fraction
- Short-chain alcohols
Correct Answer: Paraffin wax
Q44. For topical antiseptic preparations requiring a non‑aqueous vehicle, paraffins are chosen because they:
- Provide an antimicrobial mechanism by release of iodine
- Serve as an inert vehicle that limits water activity
- Act as surfactants to solubilize antiseptics
- Support microbial growth to maintain flora
Correct Answer: Serve as an inert vehicle that limits water activity
Q45. Which statement about the pharmacopoeial monographs for paraffins is correct?
- They include specifications for melting point, color, odour, and sulfur content
- They only specify biological potency
- They require paraffins to have high iodine values
- They mandate presence of free fatty acids
Correct Answer: They include specifications for melting point, color, odour, and sulfur content
Q46. In manufacturing, the term “white oil” usually refers to:
- Impure crude oil
- Highly refined mineral oil for pharmaceutical/cosmetic use
- Olive oil
- Engine lubricating oil
Correct Answer: Highly refined mineral oil for pharmaceutical/cosmetic use
Q47. Which patient population should be given special caution when prescribing liquid paraffin as a laxative?
- Healthy young adults with no aspiration risk
- Infants and elderly with swallowing or aspiration risk
- Patients with hypertension only
- Individuals with high exercise tolerance
Correct Answer: Infants and elderly with swallowing or aspiration risk
Q48. How does microcrystalline wax improve formulation properties compared to ordinary paraffin wax?
- By lowering melting range and increasing brittleness
- By increasing tack, viscosity and adhesion due to smaller crystals
- By making the formulation water soluble
- By dramatically increasing unsaturation
Correct Answer: By increasing tack, viscosity and adhesion due to smaller crystals
Q49. Which assay result would indicate contamination of a paraffin sample with polar impurities?
- Unchanged refractive index
- Increased acid value or colour change
- Zero iodine value
- Lowered molecular weight distribution only
Correct Answer: Increased acid value or colour change
Q50. Best practice when formulating a topical drug with paraffin bases to ensure patient acceptability includes:
- Using unrefined paraffins for strong odour
- Selecting pharmaceutical‑grade, deodorized paraffins and adjusting consistency
- Maximizing paraffin concentration to 100% to avoid spreadability issues
- Ignoring melting point and rheology tests
Correct Answer: Selecting pharmaceutical‑grade, deodorized paraffins and adjusting consistency
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