Q.1 Which of the following alcohols is primary?
CH3CH2OH
CH3CHOHCH3
(CH3)3COH
CH3OH2
Explanation - A primary alcohol has the –OH group attached to a carbon which is bonded to only one other carbon. CH3CH2OH is primary.
Correct answer is: CH3CH2OH
Q.2 Phenol can undergo electrophilic substitution more easily than benzene because:
It has a –OH group which activates the ring
It is more acidic
It is less stable
It forms hydrogen bonds
Explanation - The –OH group is an electron-donating group via resonance, which activates the benzene ring towards electrophilic substitution.
Correct answer is: It has a –OH group which activates the ring
Q.3 Which reagent is used for the Lucas test to differentiate alcohols?
ZnCl2 + HCl
Na
PCl5
K2Cr2O7/H2SO4
Explanation - The Lucas reagent (ZnCl2 in concentrated HCl) is used to test alcohols based on their reactivity to form alkyl chlorides.
Correct answer is: ZnCl2 + HCl
Q.4 Methoxybenzene is commonly known as:
Phenol
Anisole
Benzyl alcohol
Toluene
Explanation - Methoxybenzene (C6H5OCH3) is commonly called Anisole, an ether with a methoxy group attached to a benzene ring.
Correct answer is: Anisole
Q.5 Which alcohol will give a positive Tollens’ test?
CH3CH2OH
CH3CHOHCH3
CH3CHO
C6H5CH2OH
Explanation - Tollens’ reagent oxidizes aldehydes to carboxylic acids, giving a silver mirror. CH3CHO is an aldehyde.
Correct answer is: CH3CHO
Q.6 Which alcohol is most acidic?
CH3OH
C2H5OH
C6H5OH
(CH3)3COH
Explanation - Phenol (C6H5OH) is more acidic than alcohols due to resonance stabilization of its phenoxide ion.
Correct answer is: C6H5OH
Q.7 Which ether is commonly used as a solvent in organic reactions?
Diethyl ether
Methanol
Phenol
Ethanol
Explanation - Diethyl ether is a common organic solvent due to its low polarity and ability to dissolve a wide range of compounds.
Correct answer is: Diethyl ether
Q.8 Reaction of phenol with bromine water gives:
No reaction
2,4,6-tribromophenol
Bromoform
Phenoxide ion
Explanation - Phenol undergoes electrophilic substitution with bromine to give a white precipitate of 2,4,6-tribromophenol.
Correct answer is: 2,4,6-tribromophenol
Q.9 Which alcohol cannot be oxidized by PCC?
CH3CH2OH
CH3CHOHCH3
(CH3)3COH
C6H5CH2OH
Explanation - Tertiary alcohols do not have a hydrogen on the carbon bearing –OH and cannot be oxidized by PCC.
Correct answer is: (CH3)3COH
Q.10 Diethyl ether is prepared from ethanol using which reaction?
Dehydration with H2SO4
Oxidation with KMnO4
Substitution with NaCl
Reduction with LiAlH4
Explanation - Ethanol undergoes acid-catalyzed dehydration to give diethyl ether at lower temperatures (140°C).
Correct answer is: Dehydration with H2SO4
Q.11 Which compound is more soluble in water?
CH3OH
CH3CH2CH2CH2OH
C6H5OH
C6H5OCH3
Explanation - Methanol is highly soluble in water due to hydrogen bonding. Solubility decreases with longer chains and aromatic groups.
Correct answer is: CH3OH
Q.12 Phenoxide ion is stabilized by:
Inductive effect
Resonance
Hyperconjugation
Van der Waals forces
Explanation - The negative charge on the oxygen in phenoxide ion is delocalized over the aromatic ring by resonance, stabilizing it.
Correct answer is: Resonance
Q.13 Which alcohol reacts fastest in the Lucas test?
Primary alcohol
Secondary alcohol
Tertiary alcohol
Phenol
Explanation - Tertiary alcohols react instantly with Lucas reagent to form alkyl halides, while secondary reacts slowly and primary reacts very slowly.
Correct answer is: Tertiary alcohol
Q.14 Ether cleavage by HI gives:
Alcohols
Alkyl iodides
Ketones
Aldehydes
Explanation - Ethers react with hydrogen halides like HI to give alkyl halides and alcohols.
Correct answer is: Alkyl iodides
Q.15 Which of the following alcohols will give a positive iodoform test?
CH3CH2OH
CH3CH(OH)CH3
C6H5CH2OH
CH3OH
Explanation - Secondary alcohols with a methyl group attached to the carbon bearing –OH (CH3CH(OH)CH3) give a yellow precipitate of iodoform.
Correct answer is: CH3CH(OH)CH3
Q.16 Phenol reacts with NaOH but benzene does not because:
Phenol is acidic
Benzene is basic
Phenol is a stronger base
Benzene is soluble in NaOH
Explanation - Phenol is acidic due to resonance stabilization of the phenoxide ion and reacts with NaOH to form sodium phenoxide.
Correct answer is: Phenol is acidic
Q.17 Williamson ether synthesis involves:
Alcohol + Alkyl halide + Base
Alcohol + Acid + Heat
Ether + HI
Phenol + Bromine
Explanation - Williamson synthesis is the nucleophilic substitution of an alkoxide ion with an alkyl halide to form an ether.
Correct answer is: Alcohol + Alkyl halide + Base
Q.18 Which is the least reactive toward electrophilic substitution?
Phenol
Anisole
Benzene
Toluene
Explanation - Benzene has no activating groups, so it is less reactive compared to phenol, anisole, and toluene which have electron-donating groups.
Correct answer is: Benzene
Q.19 Which alcohol is most resistant to oxidation?
Primary alcohol
Secondary alcohol
Tertiary alcohol
Benzyl alcohol
Explanation - Tertiary alcohols do not have a hydrogen on the carbon bearing the –OH group and cannot be easily oxidized.
Correct answer is: Tertiary alcohol
Q.20 Phenol reacts with concentrated HNO3 to give:
Mononitrophenol
Dinitrophenol
Trinitrophenol
No reaction
Explanation - Phenol undergoes nitration easily, producing mainly 2,4-dinitrophenol under controlled conditions.
Correct answer is: Dinitrophenol
Q.21 Which alcohol forms a violet complex with I2 in the presence of NaOH?
CH3CH2OH
CH3CH(OH)CH3
CH3OH
C6H5CH2OH
Explanation - Iodoform test is positive for alcohols with a methyl group attached to the carbon bearing –OH, giving a violet complex of iodine initially.
Correct answer is: CH3CH(OH)CH3
Q.22 Phenols are more acidic than alcohols because:
Resonance stabilizes phenoxide ion
Alcohols are less polar
Phenols are more soluble
Alcohols have stronger H-bonds
Explanation - The negative charge on the phenoxide ion is delocalized over the aromatic ring, stabilizing it and increasing acidity.
Correct answer is: Resonance stabilizes phenoxide ion
Q.23 Which ether is more reactive towards acid cleavage?
R-O-R’ with tertiary R
R-O-R’ with primary R
Symmetrical ether
Aromatic ether
Explanation - Ethers with tertiary alkyl groups undergo cleavage more readily due to the formation of a stable tertiary carbocation.
Correct answer is: R-O-R’ with tertiary R