15 extra multiple-choice questions for Hydroxy Compounds and Ethers (12th Standard Chemistry, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Which of the following organic compounds is classified as a trihydric alcohol?
- A. Ethane-1,2-diol
- B. Ethanol
- C. Propane-1,2,3-triolCorrect
- D. Hexan-1,2,3,4,5,6-hexol
Explanation. Propane-1,2,3-triol, commonly known as glycerol, is a trihydric alcohol because its structure contains three hydroxyl groups attached to different carbon atoms.
Q2
What is the IUPAC name for neopentyl alcohol?
- A. 2,2-dimethylpropan-1-olCorrect
- B. 2-methylbutan-1-ol
- C. 2,2-dimethylbutan-1-ol
- D. 3,3-dimethylpropan-1-ol
Explanation. The longest carbon chain containing the hydroxyl group has three carbons. There are two methyl substituents at the second carbon, giving the name 2,2-dimethylpropan-1-ol.
Q3
Identify the major product formed when formaldehyde reacts with ethyl magnesium bromide followed by acid hydrolysis.
- A. Ethanol
- B. Propan-1-olCorrect
- C. Propan-2-ol
- D. Butan-1-ol
Explanation. Formaldehyde reacts with Grignard reagents to produce primary alcohols. The ethyl group from the reagent combines with the single carbon of formaldehyde to form propan-1-ol.
Q4
Which alcohol is obtained as the major product through the hydroboration-oxidation of propene?
- A. Propan-2-ol
- B. Propan-1-olCorrect
- C. Ethane-1,2-diol
- D. Isopropyl alcohol
Explanation. Hydroboration-oxidation results in the anti-Markovnikov addition of water across a double bond. For propene, the hydroxyl group attaches to the terminal carbon, producing propan-1-ol.
Q5
In Victor Meyer's test, which of the following alcohols does not produce any coloration after treatment with KOH?
- A. Ethanol
- B. Propan-2-ol
- C. 2-methylpropan-2-olCorrect
- D. Benzyl alcohol
Explanation. Tertiary alcohols like 2-methylpropan-2-ol form nitroalkanes that lack an alpha-hydrogen atom, preventing them from reacting further to form colored salts.
Q6
Which alcohol reacts immediately with Lucas reagent to produce turbidity at room temperature?
- A. Methanol
- B. Ethanol
- C. Propan-2-ol
- D. 2-methylpropan-2-olCorrect
Explanation. Tertiary alcohols like 2-methylpropan-2-ol form stable carbocations, allowing them to react instantly with the concentrated HCl and zinc chloride in Lucas reagent.
Q7
According to Saytzeff's rule, the intramolecular dehydration of butan-2-ol using concentrated sulphuric acid at 443 K yields which major product?
- A. But-1-ene
- B. But-2-eneCorrect
- C. Butane
- D. Cyclobutane
Explanation. Saytzeff's rule predicts that the more substituted and stable alkene will be the major product in elimination reactions. But-2-ene is more substituted than but-1-ene.
Q8
Alcohols generally have higher boiling points than corresponding alkanes or ethers of similar molecular mass due to:
- A. Van der Waals forces
- B. Ionic bonding
- C. Intermolecular hydrogen bondingCorrect
- D. Coordinate covalent bonding
Explanation. The polar hydroxyl group in alcohol molecules allows for the formation of strong intermolecular hydrogen bonds, which require significant energy to break during boiling.
Q9
Which of the following compounds exhibits the greatest acidic strength?
- A. Ethanol
- B. Phenol
- C. p-nitrophenolCorrect
- D. p-cresol
Explanation. p-Nitrophenol is more acidic than phenol because the electron-withdrawing nitro group stabilizes the phenoxide ion through resonance and inductive effects.
Q10
What product is formed when benzene diazonium chloride is heated with water?
- A. Benzene
- B. Chlorobenzene
- C. PhenolCorrect
- D. Nitrobenzene
Explanation. Boiling an aqueous solution of benzene diazonium chloride leads to a substitution reaction where the diazonium group is replaced by a hydroxyl group to form phenol.
Q11
In Kolbe's reaction, phenol reacts with sodium hydroxide and carbon dioxide followed by acidification to produce:
- A. Salicylaldehyde
- B. Salicylic acidCorrect
- C. Benzoic acid
- D. Phthalic acid
Explanation. In this reaction, the phenoxide ion undergoes electrophilic substitution with carbon dioxide to form ortho-hydroxybenzoic acid, which is commonly known as salicylic acid.
Q12
What is the IUPAC name for tertiary butyl methyl ether?
- A. 1-methoxy-2-methylpropane
- B. 2-methoxy-2-methylpropaneCorrect
- C. 2-methoxybutane
- D. 2-ethoxypropane
Explanation. The longest carbon chain is propane. The second carbon atom is bonded to a methyl group and a methoxy group, resulting in 2-methoxy-2-methylpropane.
Q13
Williamson ether synthesis involves the reaction between an alkoxide ion and an alkyl halide. What is the mechanism of this reaction?
- A. SN1
- B. SN2Correct
- C. Electrophilic substitution
- D. Electrophilic addition
Explanation. Williamson synthesis is a nucleophilic substitution reaction where the alkoxide ion attacks the alkyl halide in a single concerted step, following the SN2 mechanism.
Q14
When methoxyethane is heated with one equivalent of HI, the products formed are:
- A. Methanol and Ethyl iodide
- B. Iodomethane and EthanolCorrect
- C. Iodomethane and Ethyl iodide
- D. Methanol and Ethanol
Explanation. In mixed ethers with primary groups, the iodide ion preferentially attacks the smaller methyl group via an SN2 mechanism, producing iodomethane and ethanol.
Q15
Which of the following ethers is commonly used as a general anesthetic agent in surgery?
- A. Dimethyl ether
- B. Methoxybenzene
- C. Diethyl etherCorrect
- D. Diphenyl ether
Explanation. Diethyl ether is historically well-known as a general surgical anesthetic. It is also used as a solvent and as a volatile starting fluid for engines.
Frequently asked questions
How many MCQs are there in Hydroxy Compounds and Ethers?
This chapter has 15 book-back multiple-choice questions, each with the correct answer and a step-by-step explanation.
Are these 12th Standard Chemistry MCQs free to practise online?
Yes. Every question, answer and explanation here is free, and you can also take them as a timed practice test.
Where can I find the Hydroxy Compounds and Ethers book-back answers?
The correct option for each question is highlighted on this page with a worked explanation, plus a quick answer-key summary at the top.
