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Alcohols, Phenols and Ethers Set-8 MCQ Online Practice Test | Class 12 | Quiz Tweek

Alcohols, Phenols and Ethers Set-8

Practice Important MCQs for Alcohols, Phenols and Ethers — Chemistry, Class 12.

This chapter is crucial because it builds the core reactivity concepts behind ethers, phenols, and alcohols—especially acid/base behavior (acidity), nucleophilic substitution (Williamson synthesis), cleavage of ethers, electrophilic aromatic reactions on phenols, and stereochemical outcomes in substitution. These themes repeatedly appear in CBSE board exams and competitive tests (JEE/NEET) through direct reaction-choice MCQs and mechanistic reasoning.

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Q1. Which of the following reagent combinations will predominantly produce anisole ( $C_6H_5OCH_3$ ) by a Williamson ether synthesis route (minimising electrophilic aromatic alkylation)?

(A)

$NaOCH_3 + C_6H_5Br$

(B)

$C_6H_5ONa + CH_3I$

(C)

$C_6H_5OH + CH_3Cl\ \text{in presence of}\ AlCl_3$

(D)

$C_6H_5ONa + CH_3Cl\ \text{in presence of}\ AlCl_3$

Q2. Arrange the following in order of decreasing acidity (most acidic first): $p$ -nitrophenol, $o$ -nitrophenol, phenol.

(A)

$p$ -nitrophenol ;>; $o$ -nitrophenol ;>; phenol

(B)

$o$ -nitrophenol ;>; $p$ -nitrophenol ;>; phenol

(C)

phenol ;>; $p$ -nitrophenol ;>; $o$ -nitrophenol

(D)

$p$ -nitrophenol ;>; phenol ;>; $o$ -nitrophenol

Q3. Treatment of methyl tert‑butyl ether ( $CH_3\!-\!O\!-\!C(CH_3)_3$ ) with excess HI at low temperature gives which major organic product?

(A)

$CH_3I$

(B)

A mixture of $CH_3I$ and $t$ -BuI, but with $CH_3I$ predominating

(C)

No reaction under these conditions

(D)

$t$ -BuI ; (tert‑butyl iodide)

Q4. Periodic acid ( $HIO_4$ ) cleavage of the vicinal diol $C_6H_5CH(OH)CH_2OH$ (a phenyl‑substituted 1,2‑diol) yields which pair of carbonyl compounds as the primary products?

(A)

$C_6H_5CH_2OH$ and $HCHO$

(B)

$C_6H_5COOH$ and $HCHO$

(C)

$C_6H_5CHO$ and $HCHO$

(D)

$CH_3CHO$ and $C_6H_5CH_2OH$

Q5. On heating with concentrated $H_2SO_4$ , which of the following diols most readily undergoes intramolecular dehydration to give a cyclic ether (favoured ring size) rather than intermolecular dehydration to give alkenes?

(A)

$HOCH_2CH_2OH$ (1,2‑ethanediol)

(B)

$HOCH_2CH_2CH_2CH_2OH$ (1,4‑butanediol)

(C)

$HO(CH_2)_6OH$ (1,6‑hexanediol)

(D)

$HOCH_2CH_2CH_2OH$ (1,3‑propanediol)

Q6. Among the following compounds, which has the highest boiling point (consider intermolecular forces and molecular mass)?

(A)

Ethanol, $CH_3CH_2OH$

(B)

Dimethyl ether, $CH_3OCH_3$

(C)

1-Propanol, $CH_3CH_2CH_2OH$

(D)

Diethyl ether, $CH_3CH_2OCH_2CH_3$

Q7. When tert‑butyl methyl ether ( $(CH_3)_3C\!-\!O\!-\!CH_3$ ) is treated with excess HI at room temperature, which alkyl halide is formed predominantly?

(A)

Methyl iodide, $CH_3I$

(B)

tert-Butyl iodide, $(CH_3)_3CI$

(C)

A mixture of $CH_3I$ and $(CH_3)_3CI$ with $CH_3I$ predominating

(D)

No alkyl halide; elimination to isobutylene is the major outcome

Q8. Which of the following best explains why $p$ -nitrophenol is a stronger acid than $m$ -nitrophenol?

(A)

The nitro group at para position mainly shows a strong $-I$ effect, while resonance withdrawal on deprotonation is negligible; hence acidity is only slightly enhanced.

(B)

The nitro group at meta position exerts a stronger $-I$ effect so $m$ -nitrophenol should actually be stronger.

(C)

$p$ -Nitrophenol is more stable due to intramolecular hydrogen bonding in the neutral form, which makes it harder to deprotonate and therefore decreases its acidity.

(D)

On deprotonation the $p$ -nitrophenoxide ion is stabilized by resonance with the $-NO_2$ group (delocalisation of negative charge into the nitro group); in the meta isomer such resonance delocalisation is not possible and only the inductive effect operates

Q9. Phenol reacts with $Br_2$ differently in CCl $_4$ and in aqueous medium. Which statement correctly describes the typical outcomes and explains why?

(A)

In CCl $_4$ bromination of phenol gives mainly monobromination (major product $p$ -bromophenol) while in aqueous bromination phenol is partly converted to phenoxide which is far more activated and gives rapid 2,4,6-tribromophenol

(B)

In aqueous bromination bromine is deactivated by water so only monobromination occurs; CCl $_4$ being nonpolar promotes polybromination

(C)

CCl $_4$ stabilises phenoxide ion causing tribromination, whereas in water phenol is protonated and gives only para substitution

(D)

Phenol does not react with $Br_2$ in CCl $_4$ but in water it gives only 4-bromophenol due to solvation effects

Q10. Which reagent sequence is the most suitable to convert $p$ -chlorophenol into $p$ -chloroanisole (Ar–O–CH $_3$ ) without displacing the aryl chloride?

(A)

$CH_3Cl$ / $AlCl_3$ (Friedel–Crafts conditions)

(B)

Diazomethane ( $CH_2N_2$ ) in aqueous medium

(C)

$K_2CO_3$ , $CH_3I$ (acetone) — Williamson-type O‑methylation

(D)

$HBr$ (conc.) followed by $CH_3OH$

Q11. Among the following compounds, which will have the highest boiling point? (Consider hydrogen bonding and molecular size.)

(A)

$CH_3OH$ (methanol)

(B)

$CH_3CH_2OH$ (ethanol)

(C)

$CH_3OCH_3$ (dimethyl ether)

(D)

$CH_3CH_2OCH_2CH_3$ (diethyl ether)

Q12. Which of the following phenolic compounds is the strongest acid in aqueous solution? (Consider resonance, inductive effects and intramolecular hydrogen bonding.)

(A)

$o$ -Nitrophenol ( $2$ -nitrophenol)

(B)

$m$ -Nitrophenol ( $3$ -nitrophenol)

(C)

Phenol ( $C_6H_5OH$ )

(D)

$p$ -Nitrophenol ( $4$ -nitrophenol)

Q13. Treatment of ethyl isopropyl ether $CH_3CH_2\!-\!O\!-\!CH(CH_3)_2$ with excess $HBr$ (acidic cleavage) gives which alkyl bromide as the major product?

(A)

$CH_3CH_2Br$ (ethyl bromide)

(B)

Equal amounts of $CH_3CH_2Br$ and $CH_3CHBrCH_3$

(C)

$CH_3CHBrCH_3$ (isopropyl bromide)

(D)

No reaction under ordinary acidic cleavage conditions

Q14. Which of the following ethers, on treatment with $HBr$ at moderate temperature, will give benzyl bromide ( $C_6H_5CH_2Br$ ) as the major alkyl bromide?

(A)

$C_6H_5CH_2\!-\!O\!-\!CH_3$ (benzyl methyl ether)

(B)

$C_6H_5\!-\!O\!-\!CH_3$ (anisole)

(C)

$CH_3CH_2\!-\!O\!-\!CH_2CH_3$ (diethyl ether)

(D)

$(CH_3)_3C\!-\!O\!-\!CH_3$ (tert‑butyl methyl ether)

Q15. Which alcohol will give a racemic alkyl bromide on treatment with conc. $HBr$ (due to carbocation formation) but will give the corresponding bromide with inversion of configuration when treated with $PBr_3$ (SN2 pathway)?

(A)

$CH_3CH_2CH_2CH_2OH$ (1-butanol)

(B)

$C_6H_5CH(OH)CH_3$ (1-phenylethanol)

(C)

$(CH_3)_3C\!-\!OH$ (tert‑butyl alcohol)

(D)

$C_6H_{11}OH$ (cyclohexanol)

...and 5 more challenging questions available in the interactive simulator.

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