Astringents: Zinc sulphate MCQs With Answer

Zinc sulphate is a widely used pharmaceutical astringent with applications in topical formulations, ophthalmology, and antiseptic therapy. This focused resource provides B. Pharm students with comprehensive Zinc sulphate MCQs with answers, emphasizing pharmacology, pharmaceutics, mechanism of action, dosage forms, stability, pharmacokinetics, therapeutic uses, adverse effects and regulatory considerations. Each question tests practical knowledge on formulation chemistry, pH effects, complexation, compatible excipients, safety profiles, and clinical indications to strengthen exam preparation and professional competence. Structured for revision and concept mastery, these MCQs balance recall and application to simulate university and competitive assessments. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary pharmacological action of zinc sulphate when used as an astringent?

• Stimulation of collagen synthesis
• Precipitation of surface proteins and tissue contraction
• Inhibition of bacterial cell wall synthesis
• Vasodilation and increased blood flow

Correct Answer: Precipitation of surface proteins and tissue contraction

Q2. Which ionic species is responsible for the astringent activity of zinc sulphate?

• Sulfate anion (SO4 2-)
• Zinc cation (Zn2+)
• Hydronium ion (H3O+)
• Hydroxide ion (OH-)

Correct Answer: Zinc cation (Zn2+)

Q3. The most common hydrated form of pharmaceutical zinc sulphate is:

• Anhydrous zinc sulphate
• Zinc sulphate monohydrate
• Zinc sulphate heptahydrate
• Zinc sulphate decahydrate

Correct Answer: Zinc sulphate heptahydrate

Q4. What is the approximate molar mass of zinc sulphate heptahydrate (ZnSO4·7H2O)?

• 161.5 g·mol⁻¹
• 287.5 g·mol⁻¹
• 183.5 g·mol⁻¹
• 310.5 g·mol⁻¹

Correct Answer: 287.5 g·mol⁻¹

Q5. Which statement about solubility of zinc sulphate in water is correct?

• Insoluble in water
• Highly soluble in water
• Soluble only in acidic solutions
• Soluble only in organic solvents

Correct Answer: Highly soluble in water

Q6. A common topical concentration of zinc sulphate used as an astringent or ophthalmic solution is:

• 0.001%
• 0.1%–2%
• 10%–20%
• 50%

Correct Answer: 0.1%–2%

Q7. The astringent effect of zinc sulphate on skin primarily reduces which of the following?

• Collagen synthesis
• Trans-epidermal water loss
• Secretions and exudation from inflamed tissue
• Melanin production

Correct Answer: Secretions and exudation from inflamed tissue

Q8. Which of the following is a major adverse effect of topical zinc sulphate?

• Severe systemic nephrotoxicity after single topical use
• Local irritation and stinging sensation
• Permanent depigmentation
• Immediate anaphylaxis in all patients

Correct Answer: Local irritation and stinging sensation

Q9. Which incompatibility is most likely when zinc sulphate is mixed with other pharmaceutical ingredients?

• Precipitation with sulfide or phosphate ions
• Formation of an explosive complex with glycerin
• Complete neutralization producing sodium chloride
• Conversion to an ether

Correct Answer: Precipitation with sulfide or phosphate ions

Q10. Which assay method is commonly used to quantify zinc content in zinc sulphate samples in pharmaceutical analysis?

• Complexometric titration with EDTA
• Gravimetric precipitation as silver salt
• Acid-base titration with NaOH
• Karl Fischer titration

Correct Answer: Complexometric titration with EDTA

Q11. Why is zinc sulphate sometimes preferred over more aggressive antiseptics for minor skin weeping?

• It promotes heavy desiccation that destroys viable tissue
• It reduces exudation without cytotoxic effects seen with some antiseptics
• It has systemic antibiotic action
• It permanently stains the skin preventing infection

Correct Answer: It reduces exudation without cytotoxic effects seen with some antiseptics

Q12. Which property of zinc sulphate solutions affects compatibility with certain excipients and containers?

• High alkalinity (pH > 12)
• Low viscosity
• Ionic nature and tendency to hydrolyse, giving mildly acidic solutions
• High volatility

Correct Answer: Ionic nature and tendency to hydrolyse, giving mildly acidic solutions

Q13. What is a common preservative consideration when formulating aqueous zinc sulphate solutions?

• Preservatives are never needed because zinc sulphate is bactericidal at all concentrations
• Choose preservatives compatible with divalent cations to avoid precipitation
• Add strong acids to ensure preservative activity
• Only alcohol can be used as preservative

Correct Answer: Choose preservatives compatible with divalent cations to avoid precipitation

Q14. In ophthalmic preparations containing zinc sulphate, which formulation aspect is most critical?

• Ensuring the solution is hypertonic to facilitate absorption
• Maintaining sterility and appropriate tonicity and pH
• Adding emollients to reduce tearing
• Using oil-based vehicles to increase residence time

Correct Answer: Maintaining sterility and appropriate tonicity and pH

Q15. Which physiological role of zinc supports its topical use for wound management?

• Essential cofactor for enzymes involved in DNA synthesis and tissue repair
• Acts as a potent systemic anticoagulant
• Blocks oxygen delivery to tissues
• Irreversibly damages fibroblasts

Correct Answer: Essential cofactor for enzymes involved in DNA synthesis and tissue repair

Q16. Which storage condition is best for zinc sulphate heptahydrate powder in a pharmacy?

• Open container in a humid area
• Air-tight container in a cool, dry place
• Exposed to sunlight to prevent degradation
• Stored in strong alkaline solution

Correct Answer: Air-tight container in a cool, dry place

Q17. Why might a zinc sulphate solution become cloudy or show precipitate on standing?

• Formation of zinc hydroxide due to reaction with carbonates or alkalis
• Spontaneous polymerization to insoluble polymers
• Evaporation of sulfate ions
• Conversion to gaseous zinc at room temperature

Correct Answer: Formation of zinc hydroxide due to reaction with carbonates or alkalis

Q18. Which of the following analytical techniques can be used to measure trace zinc in formulation quality control?

• UV-visible spectrophotometry with appropriate ligand
• Polarimetry
• Gas chromatography with flame ionization detector
• Refractometry

Correct Answer: UV-visible spectrophotometry with appropriate ligand

Q19. The mechanism by which zinc ions exert mild antimicrobial effects includes:

• Inhibiting bacterial protein synthesis by direct ribosomal cleavage
• Precipitating and denaturing microbial surface proteins and disrupting membranes
• Acting as a DNA intercalating agent
• Generating free radicals to lyse cells

Correct Answer: Precipitating and denaturing microbial surface proteins and disrupting membranes

Q20. For oral zinc sulphate used as a supplement, a common side effect at higher doses is:

• Constipation only
• Gastrointestinal irritation and nausea
• Immediate hair loss within hours
• Marked hypoglycemia

Correct Answer: Gastrointestinal irritation and nausea

Q21. In dosage form design, adding which excipient to a zinc sulphate topical solution might risk precipitation?

• Polyethylene glycol (PEG) polymers
• Sodium phosphate buffer
• Propylene glycol
• Glycerin

Correct Answer: Sodium phosphate buffer

Q22. Which pH range is generally acceptable for ophthalmic zinc sulphate solutions to minimize irritation?

• pH 2–3
• pH 5–8
• pH 10–12
• pH 12–14

Correct Answer: pH 5–8

Q23. Which statement about systemic absorption of topical zinc sulphate is correct?

• Topical zinc sulphate always leads to toxic systemic zinc levels
• Systemic absorption is minimal for intact skin but can increase with large areas or damaged skin
• Topical zinc sulphate is converted to elemental zinc and absorbed readily
• Systemic absorption is the primary mechanism of action for topical astringency

Correct Answer: Systemic absorption is minimal for intact skin but can increase with large areas or damaged skin

Q24. Which counter-ion in formulations should be avoided to prevent formation of insoluble zinc salts?

• Sulfate
• Chloride
• Phosphate
• Nitrate

Correct Answer: Phosphate

Q25. When preparing a sterile ophthalmic solution of zinc sulphate, which sterilization method is most appropriate for final solution if heat sensitive excipients are absent?

• Dry heat sterilization at 180°C
• Autoclaving (moist heat under pressure)
• Gamma irradiation of the packaged solution
• Boiling in open vessel

Correct Answer: Autoclaving (moist heat under pressure)

Q26. Which of the following correctly describes how zinc sulphate contributes to reduced weeping in skin lesions?

• By dissolving cellular membranes to allow fluid to escape
• By protein coagulation at the surface, creating a barrier and reducing capillary leakage
• By increasing local blood flow and inflammation
• By enzymatically digesting exudate

Correct Answer: By protein coagulation at the surface, creating a barrier and reducing capillary leakage

Q27. In a formulation containing zinc sulphate, which chelating agent would most likely reduce free Zn2+ concentration and affect activity?

• Sodium chloride
• EDTA
• Sorbitol
• Hydroxyethylcellulose

Correct Answer: EDTA

Q28. Which color change might indicate contamination of a zinc sulphate preparation with sulfide ions?

• Formation of a white precipitate
• Development of a black precipitate (zinc sulfide)
• Solution turns bright yellow due to sulfate oxidation
• Magenta color due to complexation with organic matter

Correct Answer: Development of a black precipitate (zinc sulfide)

Q29. Which regulatory consideration is important when listing zinc sulphate in a B. Pharm curriculum for formulations?

• Its monograph specifications in pharmacopeias (identity, assay, purity)
• That it is unregulated and needs no documentation
• That it is classified as a controlled narcotic
• Exemption from stability testing

Correct Answer: Its monograph specifications in pharmacopeias (identity, assay, purity)

Q30. Incompatibility with which common topical ingredient might reduce zinc sulphate effectiveness?

• Aqueous glycerin
• Tannic acid leading to insoluble tannates
• Low concentrations of benzalkonium chloride
• Non-ionic surfactants

Correct Answer: Tannic acid leading to insoluble tannates

Q31. Which pharmacokinetic concept is least relevant for topical zinc sulphate intended as an astringent?

• Local residence time on skin
• Systemic bioavailability after topical use on intact skin
• Absorption across mucous membranes when applied ocularly
• Hepatic first-pass metabolism

Correct Answer: Hepatic first-pass metabolism

Q32. Which laboratory test can verify the presence of Zn2+ ions qualitatively?

• Flame test producing red flame
• Formation of a white to yellow precipitate with sodium hydroxide, soluble in excess
• Beilstein test producing green flame
• Silica gel spot test with iodine

Correct Answer: Formation of a white to yellow precipitate with sodium hydroxide, soluble in excess

Q33. Which of the following therapeutic uses is NOT commonly associated with topical zinc sulphate?

• Treatment of minor eye irritations and conjunctivitis
• Astringent for moist dermatitis
• Primary systemic antibiotic for sepsis
• Reduction of skin exudation

Correct Answer: Primary systemic antibiotic for sepsis

Q34. Which excipient would be most suitable to adjust tonicity in an ophthalmic zinc sulphate solution?

• Sodium chloride
• Povidone
• Lanolin
• Calamine powder

Correct Answer: Sodium chloride

Q35. For a zinc sulphate topical lotion intended for moist weeping lesions, which formulation objective is most important?

• Maximize oil content to occlude the lesion
• Provide appropriate astringency while maintaining mildness and acceptable pH
• Ensure complete systemic absorption
• Include strong solvents to penetrate dermis deeply

Correct Answer: Provide appropriate astringency while maintaining mildness and acceptable pH

Q36. Which systemic interaction is a concern with chronic high-dose zinc supplementation rather than topical application?

• Induction of vitamin C deficiency
• Copper deficiency due to competitive absorption
• Excessive iron absorption
• Hypermagnesemia

Correct Answer: Copper deficiency due to competitive absorption

Q37. Which of the following statements about zinc sulphate stability in solution is correct?

• It is stable at very high pH and forms stable complexes
• It can hydrolyze and is more stable in slightly acidic to neutral media
• It sublimes at room temperature, so airtight bottles are unnecessary
• It reacts with glass to produce silicates

Correct Answer: It can hydrolyze and is more stable in slightly acidic to neutral media

Q38. When teaching dosage calculations, converting 1% w/v zinc sulphate solution means:

• 1 gram of zinc sulphate in 100 mL of solution
• 1 gram of zinc sulphate in 1 mL of solution
• 10 grams in 100 mL of solution
• 0.1 gram in 1000 mL

Correct Answer: 1 gram of zinc sulphate in 100 mL of solution

Q39. Which preservative is often avoided in formulations with divalent metal ions like Zn2+ due to complexation?

• Benzalkonium chloride
• Phenol
• Thimerosal
• Parabens in high concentration

Correct Answer: Thimerosal

Q40. Which statement best explains why zinc sulphate solutions may be slightly acidic?

• Because Zn2+ hydrolyzes water producing H+ and raising pH
• Because sulfate anion is a strong acid and lowers pH
• Because the salt releases free elemental zinc which is acidic
• Because it produces hydroxide ions in solution

Correct Answer: Because Zn2+ hydrolyzes water producing H+ and raising pH

Q41. For a multi-dose ophthalmic product containing zinc sulphate, which quality test is essential?

• Test for flammability
• Sterility and preservative efficacy testing
• Determination of particle size distribution in the oil phase
• Testing for radioactivity

Correct Answer: Sterility and preservative efficacy testing

Q42. Which is a likely visual observation if zinc sulphate solution is contaminated with carbonate impurities?

• Clear solution with lowered pH
• Formation of white precipitate of zinc carbonate or hydroxide
• Solution turns bright blue
• No visible change occurs

Correct Answer: Formation of white precipitate of zinc carbonate or hydroxide

Q43. Which of the following is a correct clinical caution for topical zinc sulphate use?

• Use on large, unbroken burn areas without monitoring
• Avoid use on deep puncture wounds and severe burns until proper debridement and assessment
• Safe to use intravascularly
• Contraindicated for any ocular application

Correct Answer: Avoid use on deep puncture wounds and severe burns until proper debridement and assessment

Q44. In lecture, which molecular property of zinc explains its ability to coordinate with proteins and enzymes?

• Its large ionic radius preventing interaction
• Its divalent cationic nature and ability to form coordinate bonds with ligands
• Its inability to form coordination complexes
• Its status as an anion in biological systems

Correct Answer: Its divalent cationic nature and ability to form coordinate bonds with ligands

Q45. Which of the following clinical uses aligns with zinc sulphate’s astringent properties?

• Treatment for systemic bacterial infections as monotherapy
• Management of moist eczema and minor oozing dermatoses
• Replacing inhaled bronchodilators
• Permanent hair dyeing

Correct Answer: Management of moist eczema and minor oozing dermatoses

Q46. Which laboratory precaution is important when handling zinc sulphate powder during compounding?

• Avoid inhalation and use dust control as it can irritate respiratory tract
• No special precautions are necessary beyond gloves
• Heat vigorously to reduce dust
• Mix with strong bases to neutralize

Correct Answer: Avoid inhalation and use dust control as it can irritate respiratory tract

Q47. Which primary learning outcome is most relevant when B. Pharm students study zinc sulphate as an astringent?

• Ability to synthesize zinc metal from ore
• Understanding formulation considerations, stability, compatibility and clinical applications
• Designing nuclear reactors using zinc
• Marketing strategies for heavy metals

Correct Answer: Understanding formulation considerations, stability, compatibility and clinical applications

Q48. During formulation, which test helps confirm that zinc sulphate remains dissolved and bioavailable in an aqueous product?

• Partition coefficient determination in octanol
• Clarity and turbidity testing plus assay for Zn2+ concentration
• Melting point determination
• Gas evolution upon standing

Correct Answer: Clarity and turbidity testing plus assay for Zn2+ concentration

Q49. Which historical ophthalmic application was zinc sulphate commonly used for?

• As an intraocular lens material
• Topical drops for mild conjunctivitis and eye irritation
• Systemic treatment for glaucoma
• As a miotic agent to constrict pupils permanently

Correct Answer: Topical drops for mild conjunctivitis and eye irritation

Q50. For exam preparation, which study strategy is most effective when learning about zinc sulphate astringents?

• Memorize only concentrations without understanding compatibility or mechanism
• Integrate knowledge of chemistry, formulation, pharmacology, and clinical use with practice MCQs
• Rely solely on vendor brochures for formulation advice
• Skip practical problem-solving and focus only on theory

Correct Answer: Integrate knowledge of chemistry, formulation, pharmacology, and clinical use with practice MCQs