Structure and uses of acetone MCQs With Answer

Acetone (propan-2-one) is a simple ketone (C3H6O) central to pharmaceutical chemistry as a solvent, reagent, and cleaning agent. This introduction focuses on acetone structure and uses, emphasizing physical and chemical properties, spectroscopy (IR, 1H/13C NMR), keto–enol behavior, reactivity (aldol condensations, enolate chemistry, formation of ketals), formulation roles, analytical methods (GC, IR), and safety/storage considerations relevant to B. Pharm students. Understanding polarity, volatility, flammability, compatibility with excipients, and regulatory handling helps connect theory to lab practice and manufacturing. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the molecular formula of acetone?

• C3H6O
• C2H4O
• C3H8O
• C4H8O2

Correct Answer: C3H6O

Q2. Which functional group is present in acetone?

• Aldehyde
• Keton e
• Carboxylic acid
• Alcohol

Correct Answer: Keton e

Q3. In IR spectroscopy, the carbonyl (C=O) stretch of acetone typically appears near which wavenumber?

• 1715 cm−1
• 1600 cm−1
• 1450 cm−1
• 1200 cm−1

Correct Answer: 1715 cm−1

Q4. The 1H NMR spectrum of acetone shows a singlet for the methyl protons approximately at:

• 0.9 ppm
• 2.1 ppm
• 3.8 ppm
• 7.2 ppm

Correct Answer: 2.1 ppm

Q5. The 13C NMR chemical shift for the carbonyl carbon in acetone is closest to:

• 25 ppm
• 75 ppm
• 205 ppm
• 12 ppm

Correct Answer: 205 ppm

Q6. What is the approximate boiling point of acetone at atmospheric pressure?

• 25 °C
• 56 °C
• 100 °C
• 150 °C

Correct Answer: 56 °C

Q7. The density of liquid acetone at 20 °C is approximately:

• 1.20 g/cm3
• 0.92 g/cm3
• 0.78 g/cm3
• 1.50 g/cm3

Correct Answer: 0.78 g/cm3

Q8. Is acetone miscible with water?

• No, immiscible
• Partially miscible at low temperatures only
• Yes, completely miscible
• Miscible only with boiling water

Correct Answer: Yes, completely miscible

Q9. Regarding keto–enol tautomerism, acetone at equilibrium in neutral solution exists predominantly as:

• The enol form
• Equal amounts of keto and enol
• The keto form
• Neither keto nor enol

Correct Answer: The keto form

Q10. The approximate pKa of the alpha-hydrogens of acetone (in water or DMSO reference) is closest to:

• 5
• 10
• 19–20
• 30

Correct Answer: 19–20

Q11. Self-condensation of acetone under basic conditions initially gives which product?

• Diacetone alcohol (a β-hydroxyketone)
• Acetaldehyde
• Acetic acid
• Isopropyl alcohol

Correct Answer: Diacetone alcohol (a β-hydroxyketone)

Q12. Addition of methylmagnesium bromide (CH3MgBr) to acetone followed by acid workup yields:

• Isopropanol
• tert-Butyl alcohol (2-methyl-2-propanol)
• n-Butanol
• Acetaldehyde

Correct Answer: tert-Butyl alcohol (2-methyl-2-propanol)

Q13. Which common pharmaceutical role is acetone most widely used for?

• Active pharmaceutical ingredient (API)
• Cosmetic preservative
• Solvent for extraction and formulation cleanup
• Tablet binder

Correct Answer: Solvent for extraction and formulation cleanup

Q14. How is acetone classified for fire hazard?

• Non-flammable
• Combustible only at high temperatures
• Highly flammable
• Explosive under normal conditions

Correct Answer: Highly flammable

Q15. The approximate flash point of acetone is:

• +35 °C
• 0 °C
• −20 °C
• +100 °C

Correct Answer: −20 °C

Q16. Recommended storage for acetone in a pharmaceutical facility is:

• In open buckets in direct sunlight
• In sealed, labeled containers in a cool, well‑ventilated area away from ignition sources
• Mixed with strong oxidizers to stabilize
• Stored only at elevated temperature to prevent solidification

Correct Answer: In sealed, labeled containers in a cool, well‑ventilated area away from ignition sources

Q17. Acetone is categorized as which type of solvent?

• Polar protic
• Polar aprotic
• Nonpolar
• Ionic

Correct Answer: Polar aprotic

Q18. Which property describes acetone’s ability to dissolve a wide range of substances?

• High acidity
• Strong oxidizing power
• Intermediate polarity and good solvating power
• High molecular weight

Correct Answer: Intermediate polarity and good solvating power

Q19. Which analytical method is commonly used for quantitative assay of acetone in pharmaceutical samples?

• Gas chromatography (GC)
• Polarimetry
• Gel electrophoresis
• Atomic absorption spectroscopy

Correct Answer: Gas chromatography (GC)

Q20. Reaction of acetone with ethylene glycol under acid catalysis typically yields:

• An acetal (ketal) – a 1,3-dioxolane derivative
• An ester
• An amide
• A carboxylic acid

Correct Answer: An acetal (ketal) – a 1,3-dioxolane derivative

Q21. Acetone’s resistance to oxidation under mild conditions means:

• It is easily oxidized by water
• Strong oxidants are generally required for oxidation
• It spontaneously combusts in air
• It reduces other compounds readily

Correct Answer: Strong oxidants are generally required for oxidation

Q22. Which halogenation method selectively introduces a bromine at the alpha position of acetone?

• Br2 in acidic medium or via enolate formation
• HBr addition to the carbonyl carbon
• Nitration with HNO3
• Radical chlorination at the methyl groups only

Correct Answer: Br2 in acidic medium or via enolate formation

Q23. Which household or cosmetic product commonly contains acetone?

• Toothpaste
• Nail polish remover
• Sunscreen
• Shampoo

Correct Answer: Nail polish remover

Q24. Which plastic is rapidly dissolved by acetone and often used to demonstrate solvent action?

• Polyethylene (PE)
• Polystyrene (PS)
• PTFE (Teflon)
• Polypropylene (PP)

Correct Answer: Polystyrene (PS)

Q25. Acetone behaves as a hydrogen bond:

• Donor only
• Acceptor only (via carbonyl oxygen)
• Both donor and acceptor
• Neither donor nor acceptor

Correct Answer: Acceptor only (via carbonyl oxygen)

Q26. Which lab test gives a positive result for acetone as a carbonyl compound?

• 2,4-Dinitrophenylhydrazine (2,4-DNP) test producing a colored precipitate
• Tollens’ test producing a silver mirror
• Benedict’s test for reducing sugars
• Biuret test for proteins

Correct Answer: 2,4-Dinitrophenylhydrazine (2,4-DNP) test producing a colored precipitate

Q27. Which industrial process is a major commercial source of acetone?

• Cumene (isopropylbenzene) oxidation process co‑producing phenol
• Direct hydration of ethylene
• Fermentation of sugars
• Chlorination of methane

Correct Answer: Cumene (isopropylbenzene) oxidation process co‑producing phenol

Q28. In pharmaceutical formulations, acetone is frequently used for:

• Long‑term stabilizer in aqueous injections
• Solvent during coatings, cleaning, and recrystallization
• Primary excipient in tablets
• Preservative in syrups

Correct Answer: Solvent during coatings, cleaning, and recrystallization

Q29. Which statement about acetone toxicity is most accurate?

• Extremely toxic and carcinogenic at low doses
• Relatively low acute toxicity but causes irritation and CNS effects at high exposures
• Non‑toxic and safe for ingestion
• Causes permanent organ damage at any exposure

Correct Answer: Relatively low acute toxicity but causes irritation and CNS effects at high exposures

Q30. For laboratory cleaning of pharmaceutical glassware, acetone is preferred because it:

• Leaves a sticky residue
• Evaporates rapidly and removes organic residues
• Is non-volatile and easy to rinse
• Is non-flammable

Correct Answer: Evaporates rapidly and removes organic residues

Q31. The IUPAC name of acetone is:

• Propanal
• Propan-2-one
• 2-Propanol
• Propan-1-ol

Correct Answer: Propan-2-one

Q32. Acetone vapor relative to air is:

• Lighter than air (will rapidly rise)
• Heavier than air (can accumulate at low points)
• Exactly the same density as air
• Immiscible with air

Correct Answer: Heavier than air (can accumulate at low points)

Q33. Which reducing agent converts acetone to isopropanol?

• Sodium borohydride (NaBH4)
• PCC (pyridinium chlorochromate)
• Chromic acid
• Potassium permanganate

Correct Answer: Sodium borohydride (NaBH4)

Q34. Which reagent can convert acetone into an enolate for subsequent C–C bond formation?

• Sodium hydroxide (NaOH) or LDA to form an enolate
• Hydrochloric acid only
• Sodium chloride
• Water alone

Correct Answer: Sodium hydroxide (NaOH) or LDA to form an enolate

Q35. Which statement about acetone’s polarity compared to ethyl acetate is correct?

• Acetone is more polar than ethyl acetate
• Acetone is nonpolar while ethyl acetate is polar
• Ethyl acetate is significantly more polar than acetone
• Both have identical polarity

Correct Answer: Acetone is more polar than ethyl acetate

Q36. Which metal container material is generally acceptable for storing acetone in bulk?

• Unlined copper
• Stainless steel
• Plain iron that rusts easily
• Galvanized iron that may react

Correct Answer: Stainless steel

Q37. Acetone reacts with hydrazine to form which derivative useful for carbonyl identification?

• Hydrazone
• Oxime
• Thioacetal
• Imine

Correct Answer: Hydrazone

Q38. Which statement about acetone and water mixtures is true for pharmaceutical processing?

• Acetone and water are immiscible, forming two layers
• Acetone is completely miscible with water and can be removed by distillation or evaporation
• Acetone forms a solid complex with water at room temperature
• Acetone reacts vigorously with water producing heat

Correct Answer: Acetone is completely miscible with water and can be removed by distillation or evaporation

Q39. Which of the following is a common impurity test used in acetone quality control?

• Determination of peroxide content by titration
• Chiral purity test using polarimetry
• Microbial plate count only
• Viscosity less than water

Correct Answer: Determination of peroxide content by titration

Q40. Which pharmaceutical regulatory consideration is important when using acetone in manufacturing?

• Residue limits and solvent classification (ICH residual solvent guidelines)
• Acetone cannot be used in any pharmaceutical process
• It is always classified as a class 1 solvent
• No documentation is required for its use

Correct Answer: Residue limits and solvent classification (ICH residual solvent guidelines)

Q41. Which smell best describes acetone?

• Pungent, aromatic and sweet (characteristic ketone odor)
• Odorless
• Rotten eggs
• Chlorine-like

Correct Answer: Pungent, aromatic and sweet (characteristic ketone odor)

Q42. Which technique is commonly used to remove residual acetone from solid drug substances after solvent processing?

• Sublimation at room temperature
• Vacuum drying or rotary evaporation
• Mixing with water and discarding
• Lyophilization with liquid nitrogen only

Correct Answer: Vacuum drying or rotary evaporation

Q43. Which laboratory test distinguishes a ketone (like acetone) from an aldehyde?

• Tollens’ test – aldehydes give a silver mirror, ketones typically do not
• 2,4-DNP test – ketones react but aldehydes do not
• Benedict’s test – ketones are positive, aldehydes negative
• Chromic acid test – ketones easily oxidized to carboxylic acids under mild conditions

Correct Answer: Tollens’ test – aldehydes give a silver mirror, ketones typically do not

Q44. Which synthesis route forms acetone industrially as a major co-product with phenol?

• Cumene hydroperoxide (cumene) process
• Wacker oxidation of propene
• Fermentation of acetone–butanol–ethanol (ABE) only
• Direct chlorination of propane

Correct Answer: Cumene hydroperoxide (cumene) process

Q45. Which statement about acetone and peroxide formation is correct?

• Acetone cannot form peroxides
• Acetone can form peroxides on prolonged exposure to air and light and should be tested/stabilized
• Peroxides are beneficial for storage stability of acetone
• Peroxides are only formed when acetone is mixed with acids

Correct Answer: Acetone can form peroxides on prolonged exposure to air and light and should be tested/stabilized

Q46. Which chromatographic mobile phase application is acetone commonly used for?

• As a GC solvent and occasional organic modifier in some LC applications
• As the stationary phase in HPLC columns
• Only in paper chromatography
• Never used in chromatography

Correct Answer: As a GC solvent and occasional organic modifier in some LC applications

Q47. Which of the following reactions demonstrates nucleophilic addition to the carbonyl of acetone?

• Formation of an acetal/ketal with an alcohol under acid catalysis
• Substitution at a remote methyl group only
• Purely radical chain substitution without addition
• Dehydration to an alkene without nucleophiles

Correct Answer: Formation of an acetal/ketal with an alcohol under acid catalysis

Q48. For environmental release concerns, which property of acetone is most relevant?

• High persistence in soil (non‑volatile)
• High volatility and biodegradability which reduce long‑term persistence
• Bioaccumulation in fat tissues
• Formation of stable organochlorine compounds

Correct Answer: High volatility and biodegradability which reduce long‑term persistence

Q49. Which safety measure is critical when evaporating large volumes of acetone in a lab?

• Ensure good ventilation and avoid ignition sources due to flammability
• Use open flame to speed evaporation
• Seal the area completely to trap vapors
• Always mix with hydrogen peroxide

Correct Answer: Ensure good ventilation and avoid ignition sources due to flammability

Q50. In formulation development, why might acetone be chosen as a solvent for crystallization of an API?

• Because it is nonvolatile and difficult to remove
• Because of its polarity, volatility, and ability to dissolve many organics, enabling controlled recrystallization and easy removal
• It forms covalent bonds with APIs to stabilize them
• It always gives higher melting point crystals than other solvents

Correct Answer: Because of its polarity, volatility, and ability to dissolve many organics, enabling controlled recrystallization and easy removal

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