MCQs on Alcohols, Phenols and Ethers – CBSE Class 12
MCQs on Alcohols, Phenols and Ethers – CBSE Class 12 Chemistry
Organic Chemistry | NCERT-Based | MCQs with Answers & Explanations
The following 50 Multiple Choice Questions (MCQs) are strictly aligned with the NCERT syllabus for CBSE Class 12 Chemistry.
They are presented section-wise to cover classification, nomenclature, methods of preparation, physical properties, chemical reactions, and applications of alcohols, phenols, and ethers, with clear, concept-building explanations suitable for CBSE board exam preparation.
Section A: Alcohols – Classification & Properties
Q1. Alcohols are organic compounds containing which functional group?
A. –COOH
B. –CHO
C. –OH
D. –CO–
Answer: C
Explanation:
Alcohols contain the hydroxyl (–OH) group attached to an sp³ hybridised carbon.
Q2. Which of the following is a secondary alcohol?
A. Methanol
B. Ethanol
C. Propan-2-ol
D. tert-Butanol
Answer: C
Explanation:
In propan-2-ol, the –OH group is attached to a secondary carbon atom.
Q3. Which alcohol has the highest boiling point?
A. Methanol
B. Ethanol
C. Propan-1-ol
D. tert-Butanol
Answer: C
Explanation:
Boiling point increases with molecular mass and hydrogen bonding; straight-chain alcohols boil higher.
Q4. Alcohols have higher boiling points than corresponding alkanes due to:
A. Higher molar mass
B. Strong intermolecular hydrogen bonding
C. Polarity of C–H bond
D. Presence of oxygen
Answer: B
Explanation:
Alcohol molecules form intermolecular hydrogen bonds, raising boiling points.
Q5. Which alcohol is miscible with water in all proportions?
A. Methanol
B. Butanol
C. Pentanol
D. Hexanol
Answer: A
Explanation:
Lower alcohols like methanol form strong hydrogen bonds with water.
Section B: Preparation & Reactions of Alcohols
Q6. Alcohols can be prepared from alkyl halides using:
A. Alcoholic KOH
B. Aqueous KOH
C. Sodium metal
D. H₂SO₄
Answer: B
Explanation:
Aqueous KOH causes nucleophilic substitution, forming alcohols.
Q7. Which reagent is used to convert aldehydes into alcohols?
A. KMnO₄
B. PCC
C. NaBH₄
D. K₂Cr₂O₇
Answer: C
Explanation:
NaBH₄ reduces aldehydes to primary alcohols.
Q8. Dehydration of alcohols produces:
A. Alkanes
B. Alkenes
C. Ethers
D. Aldehydes
Answer: B
Explanation:
Removal of water from alcohols forms alkenes.
Q9. Which acid is commonly used for dehydration of alcohols?
A. HNO₃
B. HCl
C. H₂SO₄
D. CH₃COOH
Answer: C
Explanation:
Concentrated sulphuric acid acts as a dehydrating agent.
Q10. Lucas test is used to distinguish between:
A. Primary and secondary alcohols
B. Secondary and tertiary alcohols
C. All three classes of alcohols
D. Aldehydes and ketones
Answer: C
Explanation:
Reaction rate with Lucas reagent differs for primary, secondary, and tertiary alcohols.
Section C: Phenols – Structure & Properties
Q11. Phenols differ from alcohols because –OH group is attached to:
A. sp³ carbon
B. sp² carbon of benzene ring
C. Carbonyl carbon
D. Alkyl carbon
Answer: B
Explanation:
In phenols, –OH is bonded directly to an aromatic sp² carbon.
Q12. Phenols are more acidic than alcohols because:
A. Presence of oxygen
B. Larger molecular mass
C. Resonance stabilization of phenoxide ion
D. Hydrogen bonding
Answer: C
Explanation:
Phenoxide ion is resonance-stabilized, increasing acidity.
Q13. Which reagent distinguishes phenol from alcohol?
A. Na metal
B. NaOH
C. HCl
D. KMnO₄
Answer: B
Explanation:
Phenols react with NaOH, whereas alcohols do not.
Q14. Phenol gives violet coloration with:
A. Bromine water
B. Ferric chloride
C. Tollens’ reagent
D. Fehling solution
Answer: B
Explanation:
Phenols form colored complexes with FeCl₃.
Q15. Phenol reacts with bromine water to form:
A. Bromobenzene
B. 2-bromophenol
C. 2,4,6-tribromophenol
D. Chlorophenol
Answer: C
Explanation:
Phenol undergoes electrophilic substitution, giving tribromophenol.
Section D: Preparation & Reactions of Phenols
Q16. Phenol is prepared from chlorobenzene by:
A. Dow’s process
B. Sandmeyer reaction
C. Wurtz reaction
D. Swarts reaction
Answer: A
Explanation:
Dow’s process converts chlorobenzene to phenol using NaOH at high temperature and pressure.
Q17. Which reaction converts phenol into salicylic acid?
A. Reimer–Tiemann reaction
B. Kolbe’s reaction
C. Friedel–Crafts reaction
D. Wurtz reaction
Answer: B
Explanation:
Kolbe’s reaction introduces –COOH group to phenol.
Q18. Phenol reacts with zinc dust to form:
A. Aniline
B. Cyclohexane
C. Benzene
D. Toluene
Answer: C
Explanation:
Zn dust reduces phenol to benzene.
Q19. The acidic nature of phenol is due to:
A. –OH group
B. Benzene ring
C. Resonance stabilization
D. Inductive effect only
Answer: C
Explanation:
Resonance stabilization of phenoxide ion enhances acidity.
Q20. Phenol is weaker acid than:
A. Ethanol
B. Water
C. Carboxylic acids
D. Methanol
Answer: C
Explanation:
Carboxylic acids are stronger due to greater resonance stabilization.
Section E: Ethers – Structure & Properties
Q21. Ethers have the general formula:
A. R–OH
B. R–CO–R
C. R–O–R
D. R–CHO
Answer: C
Explanation:
Ethers consist of two alkyl or aryl groups linked by oxygen.
Q22. Which ether is symmetrical?
A. CH₃–O–C₂H₅
B. C₂H₅–O–C₃H₇
C. CH₃–O–CH₃
D. CH₃–O–C₆H₅
Answer: C
Explanation:
Dimethyl ether has identical alkyl groups.
Q23. Ethers have lower boiling points than alcohols because:
A. They are non-polar
B. They lack hydrogen bonding
C. They have lower molar mass
D. They are volatile
Answer: B
Explanation:
Ethers cannot form intermolecular hydrogen bonds.
Q24. Which ether is used as an anesthetic?
A. Dimethyl ether
B. Diethyl ether
C. Phenyl ether
D. Methyl ethyl ether
Answer: B
Explanation:
Diethyl ether was used as a general anesthetic.
Q25. Ethers are soluble in water because:
A. They are acidic
B. They form hydrogen bonds with water
C. They are ionic
D. They react with water
Answer: B
Explanation:
Oxygen atom in ethers forms hydrogen bonds with water.
Section F: Preparation & Reactions of Ethers
Q26. Williamson ether synthesis involves reaction between:
A. Alcohol and acid
B. Alkyl halide and alkoxide
C. Alcohol and alkene
D. Ether and acid
Answer: B
Explanation:
Alkoxide ion attacks alkyl halide to form ether.
Q27. Williamson synthesis is not suitable for:
A. Primary halides
B. Secondary halides
C. Tertiary halides
D. Alkoxides
Answer: C
Explanation:
Tertiary halides undergo elimination instead of substitution.
Q28. Ethers react with excess HI to form:
A. Alcohols
B. Alkanes
C. Alkyl iodides
D. Ketones
Answer: C
Explanation:
HI cleaves ether bond forming alkyl iodides.
Q29. Which ether undergoes cleavage most easily with HI?
A. Dialkyl ether
B. Aryl–alkyl ether
C. Diaryl ether
D. Cyclic ether
Answer: B
Explanation:
Cleavage occurs at alkyl–O bond, aryl–O bond is stronger.
Q30. Anisole on treatment with HI gives:
A. Phenol and methyl iodide
B. Benzene and methanol
C. Phenol and ethanol
D. Toluene and water
Answer: A
Explanation:
HI cleaves the alkyl–O bond in anisole.
Section G: NCERT-Based Mixed MCQs
Q31. Which compound reacts fastest with Lucas reagent?
A. Methanol
B. Ethanol
C. Propan-2-ol
D. tert-Butanol
Answer: D
Explanation:
Tertiary alcohols react immediately due to stable carbocation.
Q32. Which alcohol gives aldehyde on oxidation?
A. Primary alcohol
B. Secondary alcohol
C. Tertiary alcohol
D. Phenol
Answer: A
Explanation:
Primary alcohols oxidize first to aldehydes.
Q33. Phenol does not undergo:
A. Electrophilic substitution
B. Esterification
C. Nucleophilic substitution
D. Oxidation
Answer: C
Explanation:
Phenol does not readily undergo nucleophilic substitution.
Q34. Which compound gives iodoform test?
A. Methanol
B. Ethanol
C. Phenol
D. Ether
Answer: B
Explanation:
Ethanol forms acetaldehyde, giving iodoform test.
Q35. Which alcohol is least acidic?
A. Methanol
B. Ethanol
C. Phenol
D. tert-Butanol
Answer: D
Explanation:
+I effect of alkyl groups reduces acidity.
Q36. Which phenol is strongest acid?
A. Phenol
B. p-Nitrophenol
C. o-Cresol
D. p-Cresol
Answer: B
Explanation:
Electron-withdrawing –NO₂ increases acidity.
Q37. Which reagent converts phenol to picric acid?
A. Dilute HNO₃
B. Concentrated HNO₃
C. NaOH
D. Br₂ water
Answer: B
Explanation:
Strong nitration gives 2,4,6-trinitrophenol (picric acid).
Q38. Which ether shows isomerism?
A. Dimethyl ether
B. Diethyl ether
C. Methoxyethane
D. Phenyl ether
Answer: C
Explanation:
Methoxyethane shows functional isomerism with ethanol.
Q39. Which compound forms hydrogen bonds with itself?
A. Ether
B. Phenol
C. Alkene
D. Alkane
Answer: B
Explanation:
Phenol forms intermolecular hydrogen bonding.
Q40. Which alcohol is used as fuel?
A. Methanol
B. Ethanol
C. Phenol
D. Glycerol
Answer: B
Explanation:
Ethanol is widely used as a biofuel.
Q41. Which ether is aromatic?
A. Diethyl ether
B. Dimethyl ether
C. Anisole
D. Methoxyethane
Answer: C
Explanation:
Anisole contains an aryl group.
Q42. Which compound does not react with sodium metal?
A. Methanol
B. Ethanol
C. Phenol
D. Ether
Answer: D
Explanation:
Ethers lack active hydrogen.
Q43. The order of acidity is:
A. Alcohol > Phenol > Water
B. Phenol > Water > Alcohol
C. Water > Phenol > Alcohol
D. Alcohol > Water > Phenol
Answer: B
Explanation:
Resonance stabilization makes phenol more acidic.
Q44. Which alcohol cannot be oxidized easily?
A. Primary
B. Secondary
C. Tertiary
D. Allylic
Answer: C
Explanation:
Tertiary alcohols lack α-hydrogen.
Q45. Which reaction converts alcohol into ether?
A. Dehydration
B. Oxidation
C. Reduction
D. Hydrolysis
Answer: A
Explanation:
Intermolecular dehydration forms ethers.
Q46. Which compound gives blue color with FeCl₃?
A. Methanol
B. Ethanol
C. Phenol
D. Ether
Answer: C
Explanation:
Phenol forms colored complex with FeCl₃.
Q47. Which alcohol is most reactive towards dehydration?
A. Methanol
B. Ethanol
C. Propan-2-ol
D. tert-Butanol
Answer: D
Explanation:
Tertiary carbocation is most stable.
Q48. Which ether is used as solvent in Grignard reaction?
A. Dimethyl ether
B. Diethyl ether
C. Phenyl ether
D. Methoxyethane
Answer: B
Explanation:
Diethyl ether stabilizes Grignard reagents.
Q49. Which compound shows intramolecular hydrogen bonding?
A. o-Nitrophenol
B. p-Nitrophenol
C. Phenol
D. Cresol
Answer: A
Explanation:
Ortho substitution allows intramolecular H-bonding.
Q50. Alcohols react with carboxylic acids to form:
A. Aldehydes
B. Ketones
C. Esters
D. Ethers
Answer: C
Explanation:
Esterification forms esters.
✅ CBSE Exam Note:
These MCQs are 100% NCERT-aligned, concept-driven, and ideal for Class 12 board exams, revision practice, and objective tests.