Quiz Tweek

Preparing your workspace...

Alcohols Phenols and Ethers Set-9 MCQ Online Practice Test | Class 12 | Quiz Tweek

Alcohols Phenols and Ethers Set-9

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

This chapter is crucial because it builds the core ideas of intermolecular forces, acidity/basicity of alcohols and phenols, and how ethers are synthesized and cleaved. These concepts are repeatedly tested in CBSE board exams and in JEE/NEET through reaction mechanisms (SN1/SN2), directing effects in electrophilic aromatic substitution, and speciation/strength comparisons, so mastering them directly improves both theory scoring and problem-solving speed.

Minutes

Questions

1 / -0

Marking

Question Bank Preview

Q1. Between $n$ -butanol ( $CH_3CH_2CH_2CH_2OH$ ) and diethyl ether ( $CH_3CH_2OCH_2CH_3$ ), which has the higher boiling point under standard conditions and why?

(A)

A) Diethyl ether ( $CH_3CH_2OCH_2CH_3$ ) — higher b.p. because it has larger intermolecular surface area leading to greater dispersion (van der Waals) forces

(B)

B) $n$ -Butanol ( $CH_3CH_2CH_2CH_2OH$ ) — higher b.p. because intermolecular hydrogen bonding between $-$ OH groups dominates over dispersion forces in the ether

(C)

C) They have nearly identical boiling points because both have similar molecular weight and polarity

(D)

D) $n$ -Butanol ( $CH_3CH_2CH_2CH_2OH$ ) — lower b.p. because oxygen in the ether gives stronger dipole–dipole interactions than the single $-$ OH group can

Q2. Which one of the following alkyl halides will react fastest with sodium ethoxide ( $EtO^-$ ) in ethanol to give the corresponding ether by the Williamson (SN2) route?

(A)

A) 2-Bromopropane ( $CH_3CHBrCH_3$ ) — secondary bromide (SN2 slow)

(B)

B) tert-Butyl bromide ( $(CH_3)_3CBr$ ) — tertiary (favors elimination/SN1, not Williamson)

(C)

C) Benzyl chloride ( $C_6H_5CH_2Cl$ ) — benzylic (reactive but chloride is a poorer leaving group than iodide)

(D)

D) Methyl iodide ( $CH_3I$ ) — methyl halide (fastest SN2, good leaving group)

Q3. Among the following, which compound is the strongest acid in aqueous solution? Consider resonance, inductive effects and intramolecular hydrogen bonding.

(A)

A) $p$ -Nitrophenol — nitro at para stabilises the phenoxide ion by $-I$ and resonance withdrawal (most acidic)

(B)

B) $o$ -Nitrophenol — intramolecular H-bonding stabilises neutral phenol, reducing acidity compared to $p$ -isomer

(C)

C) $m$ -Nitrophenol — nitro at meta exerts mainly $-I$ effect (less stabilisation of phenoxide than para)

(D)

D) Phenol (unsubstituted) — no electron-withdrawing group (least acidic of the four)

Q4. Four alcohols are given: 1-butanol ( $CH_3CH_2CH_2CH_2OH$ ), 2-butanol ( $CH_3CH(OH)CH_2CH_3$ ), benzyl alcohol ( $C_6H_5CH_2OH$ ) and 2-phenylethanol ( $C_6H_5CH_2CH_2OH$ ). Which of these will undergo conversion to the corresponding alkyl bromide most readily on treatment with $HBr$ at room temperature (i.e., fastest substitution under mild conditions)?

(A)

A) 1-Butanol ( $CH_3CH_2CH_2CH_2OH$ ) — primary aliphatic (slow, SN2)

(B)

B) 2-Butanol ( $CH_3CH(OH)CH_2CH_3$ ) — secondary (moderate, may require heating)

(C)

C) Benzyl alcohol ( $C_6H_5CH_2OH$ ) — benzylic (resonance-stabilised cation / fast substitution)

(D)

D) 2-Phenylethanol ( $C_6H_5CH_2CH_2OH$ ) — primary but not benzylic (slower than benzylic)

Q5. Arrange the following aromatic compounds in order of decreasing reactivity towards electrophilic aromatic substitution (nitration) under typical conditions: phenol, anisole (methoxybenzene), toluene, nitrobenzene. Which order is correct?

(A)

A) Phenol > Anisole > Nitrobenzene > Toluene

(B)

B) Phenol > Anisole > Toluene > Nitrobenzene

(C)

C) Anisole > Phenol > Toluene > Nitrobenzene

(D)

D) Phenol > Toluene > Anisole > Nitrobenzene

Q6. A 0.10 M solution of phenol is adjusted to pH 7.0. Given $pK_a(\text{phenol}) = 10.00$ , what percentage of phenol exists as phenoxide ion ( $\mathrm{PhO^-}$ )? Use $\dfrac{[\mathrm{A^-}]}{[\mathrm{HA}]} = 10^{\mathrm{pH}-pK_a}$ .

(A)

0.001%

(B)

0.01%

(C)

0.10%

(D)

10.0%

Q7. When the following unsymmetrical ethers are treated with concentrated HBr at low temperature (so that secondary reactions of any released alcohols are negligible), which of them will yield methyl bromide ( $\mathrm{CH_3Br}$ ) as the major alkyl bromide?
(i) $\mathrm{CH_3OCH_2CH_2CH_3}$ (methyl propyl ether)
(ii) $\mathrm{(CH_3)_3COCH_3}$ (tert‑butyl methyl ether)
(iii) $\mathrm{C_6H_5OCH_3}$ (anisole)

(A)

Only (i)

(B)

Only (ii)

(C)

Only (iii)

(D)

(ii) and (iii)

Q8. Arrange the following nitrophenols in order of decreasing acidity, taking into account resonance, inductive effects and possible intramolecular hydrogen bonding: $2$ ‑nitrophenol, $3$ ‑nitrophenol, $4$ ‑nitrophenol.

(A)

$2$ ‑nitrophenol $>$ $4$ ‑nitrophenol $>$ $3$ ‑nitrophenol

(B)

$3$ ‑nitrophenol $>$ $2$ ‑nitrophenol $>$ $4$ ‑nitrophenol

(C)

$2$ ‑nitrophenol $>$ $3$ ‑nitrophenol $>$ $4$ ‑nitrophenol

(D)

$4$ ‑nitrophenol $>$ $2$ ‑nitrophenol $>$ $3$ ‑nitrophenol

Q9. Which of the following phenols is expected to be the least acidic? Consider both electronic effects and steric factors that affect resonance stabilization of the phenoxide ion.

(A)

phenol ( $\mathrm{C_6H_5OH}$ )

(B)

2,6-di-tert-butylphenol ( $\mathrm{(tBu)_2C_6H_3OH}$ )

(C)

4-nitrophenol ( $\mathrm{p\!\!-\!NO_2\!-\!C_6H_4OH}$ )

(D)

4-tert-butylphenol ( $\mathrm{p\!\!-\!tBu\!-\!C_6H_4OH}$ )

Q10. Dehydration of $1$ -phenyl- $1$ -propanol ( $\mathrm{PhCH(OH)CH_2CH_3}$ ) with concentrated H $_2$ SO $_4$ proceeds via a benzylic carbocation. Which alkene will be the major product under these acidic conditions?

(A)

$\mathrm{PhCH=CHCH_3}$ (conjugated alkene)

(B)

$\mathrm{PhCH_2CH=CH_2}$ (non‑conjugated allylbenzene)

(C)

A 1:1 mixture of (opt1) and (opt2)

(D)

No alkene; rearrangement gives a saturated rearranged alcohol instead

Q11. In a Williamson ether synthesis, sodium tert-butoxide ( $\mathrm{(CH_3)_3CONa}$ ) is reacted separately with each of the following alkyl halides under SN2 conditions at 25°C. Which alkyl halide will give the highest yield of tert-butyl ether via an SN2 pathway?

(A)

$\mathrm{CH_3CH_2CH_2CH_2Br}$ (1‑bromobutane)

(B)

$\mathrm{CH_3I}$ (methyl iodide)

(C)

$\mathrm{CH_3CHBrCH_2CH_3}$ (2‑bromobutane)

(D)

$\mathrm{(CH_3)_3CBr}$ (2‑bromo‑2‑methylpropane)

Q12. When benzyl methyl ether ( $\mathrm{C_6H_5CH_2OCH_3}$ ) is treated with excess HI at room temperature, which pair of organic compounds is formed predominantly?

(A)

$\mathrm{CH_3I\ +\ C_6H_5CH_2OH}$ (methyl iodide + benzyl alcohol)

(B)

$\mathrm{CH_3OH\ +\ C_6H_5CH_2OH}$ (methanol + benzyl alcohol)

(C)

$\mathrm{CH_3I\ +\ C_6H_5CH_2I}$ (methyl iodide + benzyl iodide)

(D)

$\mathrm{CH_3OH\ +\ C_6H_5CH_2I}$ (methanol + benzyl iodide)

Q13. A student attempts to synthesise methyl tert‑butyl ether by reacting sodium methoxide ( $\mathrm{NaOCH_3}$ ) with tert‑butyl bromide ( $\mathrm{(CH_3)_3CBr}$ ) and obtains a very low yield of the ether. Which explanation best accounts for the low yield under these conditions?

(A)

Steric hindrance at the tertiary carbon prevents an SN2 substitution; elimination (formation of isobutylene) predominates.

(B)

Methoxide is too weak a nucleophile to displace bromide at a tertiary centre under ordinary conditions.

(C)

The reaction proceeds via an SN1 pathway to give methyl tert‑butyl ether quantitatively.

(D)

Bromide is a poor leaving group in presence of methoxide so the reaction is reversible and disfavouring product.

Q14. When 1‑phenyl‑1,2‑ethanediol ( $\mathrm{C_6H_5CH(OH)CH_2OH}$ ) is treated with periodic acid ( $\mathrm{HIO_4}$ ), which pair of carbonyl compounds is obtained as the major products?

(A)

$\mathrm{C_6H_5COCH_3\ +\ HCHO}$ (acetophenone + formaldehyde)

(B)

$\mathrm{C_6H_5CH_2CHO\ +\ HCHO}$ (phenylacetaldehyde + formaldehyde)

(C)

$\mathrm{C_6H_5CHO\ +\ HCHO}$ (benzaldehyde + formaldehyde)

(D)

$\mathrm{C_6H_5CH_2OH\ +\ CH_3CHO}$ (benzyl alcohol + acetaldehyde)

Q15. Which of the following ethers is least susceptible to acid‑catalysed cleavage by concentrated HBr under standard laboratory conditions?

(A)

$\mathrm{(CH_3)_3COCH_3}$ (methyl tert‑butyl ether)

(B)

$\mathrm{C_6H_5OCH_3}$ (anisole, methoxybenzene)

(C)

$\mathrm{C_6H_5CH_2OCH_3}$ (benzyl methyl ether)

(D)

$\mathrm{CH_3CH_2OCH_2CH_3}$ (diethyl ether)

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

More Quizzes for Class 12

Explore other chapters and subjects, or view all quizzes for this class.

Quiz Tweek

Alcohols Phenols and Ethers Set-9

Question Bank Preview

More Quizzes for Class 12

Chemistry

Mathematics

Physics