Volatile oils – Clove MCQs With Answer

Volatile oils – Clove MCQs With Answer

Volatile oils, especially clove oil from Syzygium aromaticum buds, are rich essential oils dominated by phenylpropanoids such as eugenol, eugenyl acetate and beta‑caryophyllene. For B.Pharm students, studying clove volatile oil involves extraction methods (steam distillation), phytochemical composition, analytical profiling (GC‑MS, TLC, refractive index), therapeutic properties (antimicrobial, analgesic, anti‑inflammatory), formulation roles in dentistry and topical products, and safety/toxicity considerations. Emphasis on quality control, identification of adulteration and stability is crucial for pharmaceutical applications. Lab procedures, regulatory standards and commercial quality assessments form part of the curriculum. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which plant is the primary commercial source of clove volatile oil used in pharmacy?

• Syzygium aromaticum (clove) buds
• Ocimum basilicum (sweet basil)
• Cinnamomum verum (true cinnamon)
• Mentha piperita (peppermint)

Correct Answer: Syzygium aromaticum (clove) buds

Q2. Which constituent is the major phenylpropanoid in clove bud oil responsible for its analgesic and antiseptic effects?

• Geraniol
• Eugenol
• Linalool
• Caryophyllene oxide

Correct Answer: Eugenol

Q3. What is the most commonly used industrial method to obtain clove volatile oil?

• Cold pressing of dried buds
• Steam distillation of buds
• Soxhlet extraction with hexane
• Supercritical CO2 extraction of whole plant

Correct Answer: Steam distillation of buds

Q4. Which analytical technique gives a detailed fingerprint and relative percentage of clove oil components?

• Thin layer chromatography (TLC)
• Gas chromatography–mass spectrometry (GC‑MS)
• Ultraviolet spectrophotometry (UV‑Vis)
• Infrared microscopy

Correct Answer: Gas chromatography–mass spectrometry (GC‑MS)

Q5. Which functional group in eugenol is primarily responsible for the positive Ferric chloride test (color change) seen with clove oil?

• Ether linkage
• Phenolic hydroxyl (-OH)
• Allylic double bond
• Carbonyl group

Correct Answer: Phenolic hydroxyl (-OH)

Q6. Which of the following is a common pharmacological action of clove oil used therapeutically?

• Beta‑adrenergic stimulation
• Local anesthetic and analgesic activity
• Systemic hypoglycemic effect
• Cholinesterase activation

Correct Answer: Local anesthetic and analgesic activity

Q7. Eugenyl acetate in clove oil is best described as which type of compound?

• A phenolic ester
• A saturated hydrocarbon
• A diterpenoid alcohol
• A flavonoid glycoside

Correct Answer: A phenolic ester

Q8. Which parameter is commonly measured as part of physicochemical quality control for clove oil?

• Melting point
• Refractive index
• pH of oil
• Ash value

Correct Answer: Refractive index

Q9. The antimicrobial action of eugenol is primarily due to which mechanism?

• Inhibition of DNA gyrase only
• Disruption of microbial cell membranes and protein denaturation
• Blockade of folic acid synthesis exclusively
• Chelation of essential metal ions in microbes

Correct Answer: Disruption of microbial cell membranes and protein denaturation

Q10. Which part of Syzygium aromaticum is primarily used for commercial clove oil production?

• Leaves
• Roots
• Buds
• Seeds

Correct Answer: Buds

Q11. Which physical property indicates clove oil is practically insoluble in water?

• High refractive index
• Low aqueous solubility
• Positive optical rotation
• High melting point

Correct Answer: Low aqueous solubility

Q12. During GC‑MS analysis of clove oil, which peak would typically be the most abundant?

• Alpha‑pinene
• Eugenol
• Limonene
• Menthol

Correct Answer: Eugenol

Q13. Which stability precaution is most appropriate for storing clove volatile oil in a pharmacy laboratory?

• Store in clear plastic bottles at room temperature
• Store in amber glass bottles, protected from light and heat
• Freeze at −20°C in polypropylene tubes
• Add strong acid to maintain pH below 2

Correct Answer: Store in amber glass bottles, protected from light and heat

Q14. Which test would best detect adulteration of clove oil with low‑cost synthetic phenols?

• Measurement of ash value
• GC‑MS chemical profile comparison
• Determination of moisture content
• Color of aqueous extract

Correct Answer: GC‑MS chemical profile comparison

Q15. In pharmaceutical formulations, clove oil is commonly used as an excipient for which purpose?

• Buccal analgesic and flavoring agent
• Systemic antihypertensive agent
• Oral anticoagulant
• Parenteral preservative

Correct Answer: Buccal analgesic and flavoring agent

Q16. Which biosynthetic pathway leads to eugenol production in clove plants?

• Shikimate/phenylpropanoid pathway from phenylalanine
• Mevalonate pathway exclusively from acetyl‑CoA
• Polyketide pathway from malonyl‑CoA
• Nonribosomal peptide synthesis

Correct Answer: Shikimate/phenylpropanoid pathway from phenylalanine

Q17. Which safety concern is most associated with eugenol when used topically or in high doses?

• Severe hyperglycemia
• Skin sensitization and potential hepatotoxicity at high doses
• Permanent hearing loss
• Immediate renal failure at therapeutic doses

Correct Answer: Skin sensitization and potential hepatotoxicity at high doses

Q18. What is a common pharmaceutical method to quantify eugenol content in clove oil?

• Titration with sodium hydroxide
• Gas chromatography with an internal standard
• Direct weighing of oil sample
• Colorimetric test with iodine

Correct Answer: Gas chromatography with an internal standard

Q19. Which derivative of eugenol is commonly formed during esterification reactions?

• Eugenyl acetate
• Eugenol sulfate
• Eugenol nitrate
• Eugenol chlorhydrate

Correct Answer: Eugenyl acetate

Q20. How does eugenol contribute to dental applications?

• Acts as a systemic antibiotic when swallowed
• Provides local analgesia and antiseptic action in dental pastes and cements
• Replaces fluoride for enamel remineralization
• Functions as a calcium channel blocker in pulpal blood flow

Correct Answer: Provides local analgesia and antiseptic action in dental pastes and cements

Q21. Which chromatographic method is useful for rapid comparison of clove oil samples on a preparative scale?

• Paper chromatography
• Thin layer chromatography (TLC)
• Ion exchange chromatography
• Size exclusion chromatography

Correct Answer: Thin layer chromatography (TLC)

Q22. Which physical measurement helps detect oxidation or polymerization changes in stored clove oil?

• Specific gravity only
• Peroxide value or increase in acid value
• Melting point elevation
• Decrease in ash content

Correct Answer: Peroxide value or increase in acid value

Q23. Which essential oil constituent class does beta‑caryophyllene belong to?

• Monoterpenes
• Sesquiterpenes
• Alkaloids
• Flavonoids

Correct Answer: Sesquiterpenes

Q24. Which solvent is commonly used to dissolve clove oil for thin layer chromatographic analysis?

• Water
• Petroleum ether or hexane with ethyl acetate mixtures
• Conc. sulphuric acid
• Saturated sodium chloride solution

Correct Answer: Petroleum ether or hexane with ethyl acetate mixtures

Q25. Which adverse reaction may occur if clove oil is applied undiluted to skin?

• Hypertension
• Local irritation and chemical burns
• Systemic anticoagulation
• Increased hair growth

Correct Answer: Local irritation and chemical burns

Q26. Which quality parameter helps confirm authenticity by comparing optical properties of clove oil?

• Optical rotation and refractive index
• pH of oil
• Melting point
• Viscosity at 100°C

Correct Answer: Optical rotation and refractive index

Q27. In formulation, which excipient can improve the solubility of clove oil in aqueous systems?

• Hydrophobic silica without emulsifier
• Appropriate surfactants or emulsifiers to form an emulsion
• Excess sugar to bind the oil
• Activated charcoal

Correct Answer: Appropriate surfactants or emulsifiers to form an emulsion

Q28. Which regulatory concern is important when using clove oil in over‑the‑counter products?

• Ensuring the product is radioactive free
• Labeling for potential allergens and restricting concentrations to safe levels
• Prohibiting any flavoring agents
• Mandatory parenteral testing

Correct Answer: Labeling for potential allergens and restricting concentrations to safe levels

Q29. Which laboratory observation differentiates clove bud oil from clove leaf oil?

• Bud oil has much lower eugenol content than leaf oil
• Bud oil typically shows higher eugenol percentage and characteristic GC profile compared to leaf oil
• Leaf oil is colorless while bud oil is always red
• Bud oil is completely water soluble whereas leaf oil is not

Correct Answer: Bud oil typically shows higher eugenol percentage and characteristic GC profile compared to leaf oil

Q30. Which precaution is advisable when using clove oil preparations in pregnant patients?

• Use high doses for faster effect
• Use cautiously and avoid systemic high doses unless safety is established
• Prefer intramuscular administration
• No precautions are necessary; clove oil is always safe

Correct Answer: Use cautiously and avoid systemic high doses unless safety is established

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