Alcohols, Phenols and Ethers - MCQs with Explanations

1. In the reaction $C_{6}H_{5}OCH_{3} + HBr \rightarrow$ the products are:

• (a) $C_{6}H_{5}Br$, $CH_{3}OCH_{3}$ and $H_{2}$
• (b) $C_{6}H_{5}Br$ and $CH_{3}Br$
• (c) $C_{6}H_{5}Br$ and $CH_{3}OH$
• (d) $C_{6}H_{5}OH$ and $CH_{3}Br$

Correct Answer: (d)

Explanation: Alkyl aryl ethers are cleaved at the alkyl-oxygen bond because the aryl-oxygen bond is stronger due to resonance. The reaction yields phenol and methyl bromide.

2. Which one of the following on oxidation gives a ketone?

• (a) Primary alcohol
• (b) Secondary alcohol
• (c) Tertiary alcohol
• (d) All of these.

Correct Answer: (b)

Explanation: Secondary alcohols on oxidation give ketones.

3. Dow's reaction involves:

• (a) electrophilic addition
• (b) electrophilic substitution
• (c) nucleophilic addition
• (d) nucleophilic substitution.

Correct Answer: (d)

Explanation: Dow's reaction involves the alkaline hydrolysis of chlorobenzene, which is an example of a nucleophilic substitution reaction.

4. When neo-pentyl alcohol is treated with $H_{2}SO_{4}$, a mixture of two alkenes (85: 15) is formed. Which statement is correct?

• (a) Both give same major product with HBr.
• (b) Both give same products (major) with HBr/$R_{2}O_{2}$/light.
• (c) The alkene formed in 85% concentration has higher heat of hydrogenation.
• (d) Both give same product on ozonolysis.

Correct Answer: (a)

Explanation: Both alkenes formed (2-methylbut-2-ene and 2-methylbut-1-ene) react with HBr to give the same major product (2-bromo-2-methylbutane) via the same carbocation intermediate.

5. Ethyl alcohol gives ethyl chloride with the help of:

• (a) $SOCl_{2}$
• (b) NaCl
• (c) $CaCl_{2}$
• (d) KCl.

Correct Answer: (a)

Explanation: Thionyl chloride ($SOCl_{2}$) reacts with alcohols to form alkyl chlorides, as the other products ($SO_{2}$ and HCl) are gases and escape.

6. Which of the following statements about ethers is false?

• (a) Only 1 and 2
• (b) Only 3 and 4
• (c) Only 3
• (d) None of these.

Correct Answer: (d)

Explanation: All provided statements (Ethers are Lewis bases, B.P. increases with weight, all are volatile liquids, and dimethyl ether forms H-bonds with water) are actually correct.

7. The major product obtained on interaction of phenol with sodium hydroxide and carbon dioxide is:

• (a) benzoic acid
• (b) salicylaldehyde
• (c) salicylic acid
• (d) phthalic acid.

Correct Answer: (c)

Explanation: This is the Kolbe-Schmidt reaction, which produces salicylic acid from phenol.

8. Which alcohol reacts fastest with conc. HCl and anhydrous $ZnCl_{2}$?

• (a) 1-Butanol
• (b) 2-Butanol
• (c) 2-Methylpropan-2-ol
• (d) 2-Methylpropan-1-ol.

Correct Answer: (c)

Explanation: Tertiary alcohols react fastest with Lucas reagent (conc. HCl + $ZnCl_{2}$) because they form the most stable carbocation.

9. Propan-1-ol and propan-2-ol can be best distinguished by:

• (a) oxidation with $KMnO_{4}$ followed by reaction with Fehling solution
• (b) oxidation with acidic dichromate
• (c) Lucas test
• (d) Iodoform test.

Correct Answer: (d)

Explanation: Propan-2-ol contains the $CH_{3}CH(OH)-$ group and thus gives a positive iodoform test, whereas propan-1-ol does not.

10. tert-Butyl alcohol on reaction with aluminium yields:

• (a) 2-methylpropene and hydrogen
• (b) aluminium hydroxide and oxygen
• (c) aluminium tert-butoxide and hydrogen
• (d) 2-butene and oxygen.

Correct Answer: (c)

Explanation: Alcohols react with active metals like aluminium to form alkoxides and liberate hydrogen gas.

11. Increasing order of acidic strength among phenol, cresol and p-nitrophenol is:

• (a) cresol < phenol < p-nitrophenol
• (b) p-nitrophenol < cresol < phenol
• (c) phenol < p-nitrophenol < cresol
• (d) phenol < cresol < p-nitrophenol.

Correct Answer: (a)

Explanation: Electron-withdrawing groups ($-NO_{2}$) increase acidity, while electron-donating groups ($-CH_{3}$) decrease it.

12. Ethanol produces ethoxyethane at temperature $T_{1}$ and ethene at $T_{2}$ with $H_{2}SO_{4}$. $T_{1}$ and $T_{2}$ are:

• (a) 443 K, 413 K
• (b) 413 K, 443 K
• (c) 1225 K, 780 K
• (d) It does not depend on temperature.

Correct Answer: (b)

Explanation: Dehydration of ethanol with $H_{2}SO_{4}$ yields ether at 413 K and alkene at 443 K.

13. The reaction of sodium methoxide with tert-butyl bromide gives:

• (a) tert-butyl methyl ether
• (b) butene
• (c) 2-methylpropene
• (d) both (a) and (c).

Correct Answer: (c)

Explanation: Reaction of a tertiary alkyl halide with a strong base like sodium methoxide results in elimination (forming 2-methylpropene) rather than substitution.

14. Which of the following compounds is least acidic?

• (a) Ethanol
• (b) p-Nitrophenol
• (c) Phenol
• (d) m-Nitrophenol

Correct Answer: (a)

Explanation: Phenols are much more acidic than alcohols because the phenoxide ion is stabilized by resonance.

15. Phenol on heating with zinc dust gives:

• (a) toluene
• (b) cresol
• (c) benzaldehyde
• (d) benzene.

Correct Answer: (d)

Explanation: Reduction of phenol with zinc dust produces benzene.

16. Salicylic acid is:

• (a) 2-phenylethanoic acid
• (b) 2-hydroxybenzoic acid
• (c) 3-methoxybenzoic acid
• (d) 3-aminobenzoic acid.

Correct Answer: (b)

Explanation: The systematic name for salicylic acid is 2-hydroxybenzoic acid.

17. The correct decreasing order of acidity is:

• (a) $I > II > III > IV$
• (b) $I > II > IV > III$
• (c) $I > III > II > IV$
• (d) $II > III > IV > I$

Correct Answer: (b)

Explanation: For nitrophenols, the order of acidity is: p-Nitrophenol > o-Nitrophenol > m-Nitrophenol > Phenol.

18. Which of the following is most acidic?

• (a) p-Nitrophenol
• (b) Phenol
• (c) m-Nitrophenol
• (d) o-Nitrophenol.

Correct Answer: (a)

Explanation: p-Nitrophenol is the most acidic due to the strong electron-withdrawing effect of the $-NO_{2}$ group in the para position.

19. Identify the correct order of acidic strength:

• (a) Chloroacetic acid > Phenol > Water > Alcohol > 1-Alkyne
• (b) p-Nitrophenol > Chloroacetic acid > Water > 1-Alkyne
• (c) Chloroacetic acid > p-Nitrophenol > Phenol > Water
• (d) All of these.

Correct Answer: (a)

Explanation: Carboxylic acids are stronger than phenols, which are stronger than water, followed by alcohols and then terminal alkynes.

20. In the reaction $CH_{3}CHBrCH_{3} \xrightarrow{alc. KOH} A \xrightarrow{HBr/Peroxide} B \xrightarrow{CH_{3}ONa} C$, C is:

• (a) diethyl ether
• (b) 1-methoxy propane
• (c) isopropyl alcohol
• (d) propylene glycol.

Correct Answer: (b)

Explanation: 2-bromopropane undergoes elimination to propene (A). Propene reacts with HBr in peroxide to form 1-bromopropane (B), which then reacts with sodium methoxide to yield 1-methoxypropane (C).

21. The order of reactivity of alcohols towards conc. HCl is:

• (a) $I > II > III > IV$
• (b) $I > III > II > IV$
• (c) $IV > III > II > I$
• (d) $IV > II > III > I$.

Correct Answer: (c)

Explanation: Reactivity depends on carbocation stability: Benzyl > Secondary > Primary. Electron-withdrawing fluorine atoms further destabilize the carbocation, decreasing reactivity.

22. Phenol $\xrightarrow{Zn dust} X \xrightarrow{CH_{3}Cl/AlCl_{3}} Y \xrightarrow{Alk. KMnO_{4}} Z$. Z is:

• (a) benzaldehyde
• (b) benzoic acid
• (c) benzene
• (d) toluene.

Correct Answer: (b)

Explanation: Phenol is reduced to benzene (X), which is alkylated to toluene (Y), and then oxidized to benzoic acid (Z).

23. Number of structural isomers with molecular formula $C_{3}H_{8}O$:

• (a) 1
• (b) 2
• (c) 3
• (d) 4

Correct Answer: (c)

Explanation: The three structural isomers are propan-1-ol, propan-2-ol, and ethyl methyl ether.

24. In ethers (R-O-R), the C-O-C bond angle is about 110°. This is because:

• (a) +I effect of alkyl groups
• (b) alkyl group is polar
• (c) distortion from lone pair repulsion is compensated by bulky alkyl groups
• (d) hybridisation of oxygen is different.

Correct Answer: (c)

Explanation: The repulsion between the bulky alkyl groups partially offsets the compression caused by the two lone pairs on oxygen, leading to an angle larger than in water.

25. Glycerol $\xrightarrow{HCl} X \xrightarrow{[O]} Y \xrightarrow{HCN} Z \xrightarrow{H_{2}O/H^{+}} A$. 'A' is:

• (a) citric acid
• (b) ascorbic acid
• (c) tartaric acid
• (d) saccharic acid.

Correct Answer: (a)

Explanation: Through a series of reactions (chlorination, oxidation, and cyanohydrin formation/hydrolysis), glycerol can be converted into citric acid.

26. Diethyl ether on reaction with CO in specific conditions forms:

• (a) acetic acid
• (b) carbon dioxide
• (c) ethyl propanoate
• (d) acetyl chloride.

Correct Answer: (c)

Explanation: Carbonylation of diethyl ether in the presence of $BF_{3}$ produces ethyl propanoate.

27. Phenol reacts with $Br_{2}$ in $CCl_{4}$ at low temperature to give:

• (a) m-bromophenol
• (b) o- and p-bromophenol
• (c) p-bromophenol
• (d) 2,4,6-tribromophenol.

Correct Answer: (b)

Explanation: In non-polar solvents like $CCl_{4}$ at low temperatures, phenol yields a mixture of ortho and para bromophenols.

28. Acetylation of phenol gives:

• (a) sodium salicylate
• (b) phenyl acetate
• (c) phenyl chloride
• (d) sodium phenoxide.

Correct Answer: (b)

Explanation: Reaction with acetic anhydride or acetyl chloride converts phenol to phenyl acetate.

29. When phenol is treated with $Br_{2}$ water, the product is:

• (a) o- and p-bromophenol
• (b) 2,3,4-tribromophenol
• (c) 2,4,6-tribromophenol
• (d) none of these.

Correct Answer: (c)

Explanation: Bromine water causes polybromination of phenol at all active positions, yielding 2,4,6-tribromophenol.

30. Which product is obtained by Kolbe-Schmidt reaction?

• (a) Salicylaldehyde
• (b) Cinnamic acid
• (c) Salicylic acid
• (d) Phenetole.

Correct Answer: (c)

Explanation: Salicylic acid is the product of the Kolbe-Schmidt reaction between sodium phenoxide and $CO_{2}$.

31. In the reaction $CH_{3}CH_{2}OH \xrightarrow{KMnO_{4}/H^{+}} A \xrightarrow{B/H_{2}SO_{4}} CH_{3}COOCH_{2}CH_{3}$, A and B are:

• (a) $CH_{3}CHO$ and $CH_{3}COOH$
• (b) $CH_{3}COOH$ and $CH_{3}OH$
• (c) $CH_{2}-CH_{2}$ and $CH_{3}COOH$
• (d) $CH_{3}COOH$ and $CH_{3}CH_{2}OH$.

Correct Answer: (d)

Explanation: Ethanol is oxidized to acetic acid (A). Acetic acid then reacts with ethanol (B) through esterification to produce ethyl acetate.

32. Which ether undergoes electrophilic substitution reactions?

• (a) $CH_{3}OC_{2}H_{5}$
• (b) $C_{6}H_{5}OCH_{3}$
• (c) $CH_{3}OCH_{3}$
• (d) $C_{2}H_{5}OC_{2}H_{5}$.

Correct Answer: (b)

Explanation: Anisole ($C_{6}H_{5}OCH_{3}$) has a benzene ring with an activating alkoxy group, allowing for electrophilic substitution.

33. Identify Z in $CH_{3}CH_{2}CH=CH_{2} \xrightarrow{HBr/H_{2}O_{2}} Y \xrightarrow{C_{2}H_{5}ONa} Z$:

• (a) $(CH_{3})_{2}CHOCH_{2}CH_{3}$
• (b) $CH_{3}CH_{2}CH(CH_{3})OCH_{2}CH_{3}$
• (c) $CH_{3}(CH_{2})_{3}OCH_{2}CH_{3}$
• (d) $CH_{3}(CH_{2})_{4}OCH_{3}$.

Correct Answer: (c)

Explanation: 1-butene undergoes anti-Markovnikov addition with HBr/peroxide to 1-bromobutane (Y), which then reacts with sodium ethoxide to form 1-ethoxybutane (Z).

34. Which of the following compounds has the most acidic nature?

• (a) Benzyl alcohol
• (b) Phenol
• (c) Propan-1-ol
• (d) Cyclohexanol.

Correct Answer: (b)

Explanation: Phenol is most acidic as its conjugate base (phenoxide) is resonance-stabilized.

35. Which reaction will not result in a carbon-carbon bond?

• (a) Reimer-Tiemann reaction
• (b) Cannizzaro reaction
• (c) Wurtz reaction
• (d) Friedel-Crafts acylation.

Correct Answer: (b)

Explanation: Cannizzaro reaction is a disproportionation reaction and does not form new C-C bonds like the others.

36. The acidity order for (i) Phenol, (ii) Methyl phenol, (iii) Meta-nitrophenol, and (iv) Para-nitrophenol is:

• (a) $(iv) > (iii) > (i) > (ii)$
• (b) $(iii) > (iv) > (i) > (ii)$
• (c) $(i) > (iv) > (iii) > (ii)$
• (d) $(ii) > (i) > (iii) > (iv)$.

Correct Answer: (a)

Explanation: Electron-withdrawing nitro groups increase acidity (para > meta), while electron-donating methyl groups decrease it.

37. When glycerol is treated with excess of HI, it produces:

• (a) 2-iodopropane
• (b) allyl iodide
• (c) propene
• (d) glycerol triiodide.

Correct Answer: (a)

Explanation: Reaction with excess HI converts glycerol through multiple steps into 2-iodopropane.

38. Which compounds give a positive iodoform test?

• (a) (i), (iii) and (iv)
• (b) Only (ii)
• (c) (i), (ii) and (iii)
• (d) (i) and (ii).

Correct Answer: (c)

Explanation: Ethanol (i), Acetone (ii), and Secondary alcohols with a methyl group (iii) give the iodoform test.

39. Which compound will be most readily dehydrated?

• (a) [structure a]
• (b) [structure b]
• (c) [structure c]
• (d) [structure d].

Correct Answer: (c)

Explanation: Dehydration is easier when the resulting carbocation is more stable and less affected by nearby electron-withdrawing groups.

40. Which cannot be prepared by Williamson's synthesis?

• (a) Methoxybenzene
• (b) Benzyl-p-nitrophenyl ether
• (c) Methyl tert-butyl ether
• (d) Di-tertiary butyl ether.

Correct Answer: (d)

Explanation: Williamson's synthesis involves an $S_{N}2$ attack. Attempting to use a tertiary alkyl halide results in elimination to form an alkene.

41. Which phenol derivative gives effervescence with sodium bicarbonate?

• (a) [structure a]
• (b) [structure b]
• (c) [structure c]
• (d) [structure d].

Correct Answer: (b)

Explanation: 2,4,6-trinitrophenol (picric acid) is highly acidic (pKa comparable to carboxylic acids) and can decompose $NaHCO_{3}$.

42. A compound 'A' ($C_{5}H_{12}O$) oxidizes to 'B' ($C_{5}H_{10}O$). 'B' gives a 2,4-DNP derivative but negative haloform test. A is:

• (a) Pentan-2-one precursor
• (b) Pentan-2-ol
• (c) Pentan-3-one precursor
• (d) Pentan-3-ol.

Correct Answer: (d)

Explanation: The product 'B' is a ketone ($C_{5}H_{10}O$). Since it fails the haloform test, it cannot be a methyl ketone. Thus B is pentan-3-one and A is pentan-3-ol.

43. 23 g of sodium shall react with methyl alcohol ($CH_{3}OH$) to give:

• (a) one mole of oxygen
• (b) 1/2 mole of hydrogen
• (c) one mole of hydrogen
• (d) 2 g of hydrogen.

Correct Answer: (b)

Explanation: 23 g of sodium is 1 mole. 1 mole of Na reacts with excess methanol to liberate 0.5 moles of $H_{2}$ gas.

44. How can ethyl methyl ether be obtained?

• (a) $2C_{2}H_{5}I + Ag_{2}O \rightarrow$
• (b) $C_{2}H_{5}OH + CH_{2}N_{2} \xrightarrow{HBF_{4}}$
• (c) $C_{2}H_{5}ONa + C_{2}H_{5}I$
• (d) $2C_{2}H_{5}OH \xrightarrow{Al_{2}O_{3}, 250^{\circ}C}$.

Correct Answer: (b)

Explanation: Reaction of ethanol with diazomethane in the presence of $HBF_{4}$ yields ethyl methyl ether.

45. What product is formed when but-1, 4-diol is heated with conc. $H_{2}SO_{4}$?

• (a) Furan
• (b) Oxane
• (c) Oxolane
• (d) Pyran.

Correct Answer: (c)

Explanation: Intramolecular dehydration of butan-1,4-diol yields the cyclic ether oxolane (tetrahydrofuran).