tert-Butyl ethyl ether is to be made by Williamson synthesis. Which pair of reactants gives it in good yield?

(CH₃)₃CONa and CH₃CH₂Br

(CH₃)₃CBr and CH₃CH₂ONa

(CH₃)₃CONa and (CH₃)₃CBr

Alcohols, Phenols & Ethers

10 NEET-UG practice questions on Alcohols, Phenols & Ethers, part of Chemistry. The first 10 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
Read these statements on the acid-catalysed dehydration of alcohols. A. Ease of dehydration follows the order tertiary > secondary > primary. B. Ethanol with conc. H₂SO₄ at 443 K gives ethene as the main product. C. The slowest step is the protonation of the alcohol. D. Excess ethanol with conc. H₂SO₄ at 413 K gives ethoxyethane. Which of these are correct?
1. AA, C and D only
2. BB, C and D only
3. CA and B only
4. DA, B and D only
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Answer: D · A, B and D only
Dehydration passes through a carbocation, so its ease follows carbocation stability, which makes A correct. Temperature decides the product of ethanol: ethene at 443 K (B), and the ether at 413 K with excess alcohol (D). C is wrong, because protonation is fast and loss of water to form the carbocation is the slowest step.
- A: This includes C and leaves out B, which is the standard preparation of ethene.
- B: This includes C and leaves out A, which is the standard reactivity order.
- C: This leaves out D, though the ether does form at 413 K.
Remember this
In acid dehydration, carbocation formation is the slow step; lower temperature with excess alcohol favours the ether.
Question 2 · Easy
Ethane-1,2-diol (0.2 mol) reacts completely with excess sodium. What volume of H₂ forms at STP? (Molar volume = 22.4 L)
1. A6.72 L
2. B2.24 L
3. C8.96 L
4. D4.48 L
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Answer: D · 4.48 L
Each -OH gives half a mole of H₂, so a diol gives 1 mol of H₂ per mole. So 0.2 mol of diol gives 0.2 mol of H₂, and 0.2 × 22.4 = 4.48 L.
- A: This treats the compound as a triol, taking 0.3 mol of H₂.
- B: This counts only one -OH group per molecule.
- C: This forgets that hydrogen is diatomic, taking 0.4 mol of H₂.
Remember this
Moles of H₂ with sodium equal half the moles of -OH groups present.
Question 3 · Medium
tert-Butyl ethyl ether is to be made by Williamson synthesis. Which pair of reactants gives it in good yield?
1. ACH₃CH₂ONa and CH₃CH₂Br
2. B(CH₃)₃CBr and CH₃CH₂ONa
3. C(CH₃)₃CONa and CH₃CH₂Br
4. D(CH₃)₃CONa and (CH₃)₃CBr
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Answer: C · (CH₃)₃CONa and CH₃CH₂Br
Williamson synthesis is SN2, so it needs an unhindered, primary alkyl halide. The bulky group must come in as the alkoxide, with CH₃CH₂Br as the substrate.
- A: This pair gives diethyl ether, not the required ether.
- B: A tertiary halide with a strong base eliminates to give 2-methylpropene.
- D: This pair has a tertiary halide, which eliminates, and has no ethyl group at all.
Remember this
Keep the alkyl halide primary; a tertiary halide with an alkoxide undergoes elimination and gives the alkene.
Question 4 · Easy
With Lucas reagent at room temperature, which alcohol turns cloudy immediately?
1. A2-Methylpropan-1-ol
2. B2-Methylpropan-2-ol
3. CButan-1-ol
4. DButan-2-ol
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Answer: B · 2-Methylpropan-2-ol
Lucas reagent is conc. HCl with ZnCl₂. Tertiary alcohols form the insoluble alkyl chloride at once by way of a stable carbocation. Secondary alcohols take some minutes and primary ones show no turbidity at room temperature.
- A: This is a branched primary alcohol, and branching does not change its class.
- C: This is a primary alcohol, which shows no turbidity at room temperature.
- D: This is a secondary alcohol, which needs several minutes.
Remember this
Lucas turbidity: tertiary at once, secondary in minutes, primary not at room temperature.
Question 5 · Medium
Arrange these compounds in increasing order of acid strength. A. Ethanol B. Phenol C. 4-Methylphenol D. 4-Nitrophenol
1. AA, B, C, D
2. BA, C, B, D
3. CD, B, C, A
4. DC, A, B, D
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Answer: B · A, C, B, D
Phenoxide ions are stabilised by resonance, so phenols are more acidic than ethanol. An electron-donating methyl lowers the acidity of phenol slightly, while an electron-withdrawing nitro at the para position raises it strongly.
- A: This ranks 4-methylphenol above phenol, treating methyl as electron-withdrawing.
- C: This reverses the whole order.
- D: This puts 4-methylphenol below ethanol, ignoring phenoxide resonance.
Remember this
Electron-withdrawing groups strengthen a phenol as an acid; electron-donating groups weaken it; every phenol here beats ethanol.
Question 6 · Medium
A sample of 9.4 g of phenol reacts completely with excess bromine water. What mass of the precipitate forms? (C = 12, H = 1, O = 16, Br = 80)
1. A17.3 g
2. B9.4 g
3. C25.2 g
4. D33.1 g
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Question 7 · Hard
Given below are two statements: Statement I: Anisole with HI gives phenol and methyl iodide, not iodobenzene and methanol. Statement II: tert-Butyl methyl ether with HI gives tert-butyl alcohol and methyl iodide. Choose the correct answer.
1. AStatement I is incorrect but Statement II is correct
2. BStatement I is correct but Statement II is incorrect
3. CBoth Statement I and Statement II are incorrect
4. DBoth Statement I and Statement II are correct
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Question 8 · Easy
Phenol is shaken with bromine water. What is the white precipitate?
1. A4-Bromophenol
2. B2,4,6-Tribromophenol
3. C2,4-Dibromophenol
4. D3,5-Dibromophenol
Answer and explanation in LearnFree account
Question 9 · Medium
Arrange the compounds drawn in order of increasing acid strength. A. Structure A B. Structure B C. Structure C D. Structure D
Figure: MedExams
1. AB, A, D, C
2. BB, A, C, D
3. CA, B, D, C
4. DB, D, A, C
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Question 10 · Medium
X and Y in the figure are isomeric alcohols. Given below are two statements: Statement I: With Lucas reagent at room temperature, X turns turbid almost at once, while Y does not. Statement II: On heating with concentrated acid, X dehydrates under milder conditions than Y. Choose the correct answer.
Figure: MedExams
1. AStatement I is correct but Statement II is incorrect
2. BBoth Statement I and Statement II are correct
3. CStatement I is incorrect but Statement II is correct
4. DBoth Statement I and Statement II are incorrect
Answer and explanation in LearnFree account

Alcohols, Phenols & Ethers

Ethane-1,2-diol (0.2 mol) reacts completely with excess sodium. What volume of H₂ forms at STP? (Molar volume = 22.4 L)

tert-Butyl ethyl ether is to be made by Williamson synthesis. Which pair of reactants gives it in good yield?

With Lucas reagent at room temperature, which alcohol turns cloudy immediately?

Arrange these compounds in increasing order of acid strength. A. Ethanol B. Phenol C. 4-Methylphenol D. 4-Nitrophenol

A sample of 9.4 g of phenol reacts completely with excess bromine water. What mass of the precipitate forms? (C = 12, H = 1, O = 16, Br = 80)

Given below are two statements: Statement I: Anisole with HI gives phenol and methyl iodide, not iodobenzene and methanol. Statement II: tert-Butyl methyl ether with HI gives tert-butyl alcohol and methyl iodide. Choose the correct answer.

Phenol is shaken with bromine water. What is the white precipitate?

Arrange the compounds drawn in order of increasing acid strength. A. Structure A B. Structure B C. Structure C D. Structure D

X and Y in the figure are isomeric alcohols. Given below are two statements: Statement I: With Lucas reagent at room temperature, X turns turbid almost at once, while Y does not. Statement II: On heating with concentrated acid, X dehydrates under milder conditions than Y. Choose the correct answer.