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COMEDK Alcohols, Phenols and Ethers — practice questions

Explore 30 free Alcohols, Phenols and Ethers questions in COMEDK Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Alcohols, Phenols and Ethers questions and exercises with answers

Showing questions 1–30 of 30.

How is glycerol (propane-1,2,3-triol) classified by the number of –OH groups it contains?Read the answer and worked solution →Arrange in increasing order of acidic strength: methanol, ethanol, water, phenol.Read the answer and worked solution →Ethanol is dehydrated with concentrated $\mathrm{H_2SO_4}$ at $443$ K (170 °C). What is the major product?Read the answer and worked solution →Hydrocarbons are organic compounds composed exclusively of:Read the answer and worked solution →In the presence of organic peroxides, addition of HBr to propene gives predominantly:Read the answer and worked solution →Wurtz reaction is used to prepare:Read the answer and worked solution →Match each scientist to their contributionRead the answer and worked solution →Ionic or covalent?Read the answer and worked solution →Complete the driver of bond formationRead the answer and worked solution →Single, double and triple bondsRead the answer and worked solution →True or false: Lewis structuresRead the answer and worked solution →Complete the definition of resonanceRead the answer and worked solution →Tap every bond parameter the chapter namesRead the answer and worked solution →True or false: ionic solidsRead the answer and worked solution →Assertion and reasonRead the answer and worked solution →Two are true, one is notRead the answer and worked solution →Three of these are wrong. Find the one that holds.Read the answer and worked solution →Bonded pair or lone pair?Read the answer and worked solution →Flip and pair: term with meaningRead the answer and worked solution →Spot the one that does not belongRead the answer and worked solution →Order the reasoning: why resonance is neededRead the answer and worked solution →Reading the definitions backRead the answer and worked solution →True or false: what bond parameters affectRead the answer and worked solution →Bond parameters in useRead the answer and worked solution →Which parameter answers this?Read the answer and worked solution →True or false: resonanceRead the answer and worked solution →Order the steps: draw a Lewis structureRead the answer and worked solution →Spot the one that does not belongRead the answer and worked solution →Assertion and reason: structureRead the answer and worked solution →Flip and pair: parameter with what it measuresRead the answer and worked solution →

Worked practice questions

How is glycerol (propane-1,2,3-triol) classified by the number of –OH groups it contains?

  1. Monohydric alcohol
  2. Dihydric alcohol
  3. Trihydric alcohol
  4. Phenol
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Correct answer: C. Trihydric alcohol

Glycerol has three hydroxyl groups (on C1, C2 and C3), making it a **trihydric** alcohol. Monohydric carries one –OH (e.g. ethanol) dihydric two (e.g. ethylene glycol).

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Arrange in increasing order of acidic strength: methanol, ethanol, water, phenol.

  1. ethanol < methanol < water < phenol
  2. phenol < water < ethanol < methanol
  3. methanol < ethanol < water < phenol
  4. water < methanol < ethanol < phenol
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Correct answer: A. ethanol < methanol < water < phenol

Approximate pKₐ values: phenol ≈ 10, water ≈ 15.7, methanol ≈ 15.5, ethanol ≈ 15.9. Lower pKₐ ⇒ stronger acid. Ordering ascending acidity: **ethanol < methanol < water < phenol**. **Why:** phenol's conjugate base (phenoxide) is stabilised by resonance into the aromatic ring, dramatically lowering its pKₐ versus aliphatic alcohols. Among the alcohols, the +I effect of larger alkyl groups *destabilises* the alkoxide (donates electron density) so ethanol is weaker than methanol.

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Ethanol is dehydrated with concentrated $\mathrm{H_2SO_4}$ at $443$ K (170 °C). What is the major product?

  1. Diethyl ether
  2. Acetaldehyde
  3. Ethene
  4. Methanol
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Correct answer: C. Ethene

**Temperature determines the product.** At ~170 °C with concentrated H₂SO₄, intramolecular dehydration (E1) of ethanol gives **ethene** plus water — the classic preparation of ethene from ethanol. At lower temperatures (≈ 140 °C, less acid) the reaction takes the *intermolecular* path: two ethanol molecules condense via loss of water to give **diethyl ether** instead. **Option B is therefore the answer for a *different* temperature regime — a common JEE trap.** Mechanism (E1, three steps): (i) protonation of the –OH, (ii) loss of H₂O to give a carbocation, (iii) loss of a β-proton to give the alkene.

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More Chemistry topics

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