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Free Alcohols and Phenols MCQs with Answers

535 Alcohols and Phenols MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Alcohols are classified as primary, secondary or tertiary and studied through their hydrogen bonding, acidity, oxidation and reactions with active metals, acids and halogenating agents. Phenols require separate treatment because the hydroxyl group is attached to an aromatic ring, making their acidity and electrophilic substitution different from ordinary alcohols.

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535 questions · page 18 of 27

341. The acidity of phenol is due to its_:

  • A. Nature of Benzene
  • B. Double bond in benzene ring
  • C. Nature of phenoxide ion
  • D. Hydroxyl group

Explanation: The correct reason for the acidity of phenol is C) Nature of phenoxide ion.

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Correct answer: Nature of phenoxide ion

342. Which statement is true about phenol?

  • A. It is more acidic than acetic acid
  • B. It is more acidic than ethyl alcohol
  • C. It turns red litmus blue
  • D. It does not react with sodium

Explanation: The correct statement about phenol is B) It is more acidic than ethyl alcohol.

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Correct answer: It is more acidic than ethyl alcohol

343. Identify the reaction of alcohol in which the O - H bond breaks.

  • A. Option A
  • B. Option B
  • C. Option C
  • D. Option D

Explanation: In this reaction, the OH bond of the alcohol (CH3CH2OH, ethanol) breaks as the alcohol reacts with phosphorus pentachloride (PCl5) to form…

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Correct answer: Option C

344. Which reaction shows the acidic nature of alcohol.

  • A. C2H5OH+SOCl2
  • B. C2H5OH+ NH3
  • C. C2H5OH+Na
  • D. C2H5OH+CH3MgI

Explanation: Alcohols react with active metals such as sodium, potassium etc. to form the corresponding alkoxide.

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Correct answer: C2H5OH+Na

345. The compound that reacts the slowest in Lucas test.

  • A. 1 - Pentanol
  • B. 3 - Pentanol
  • C. sec-butyl alcohol
  • D. ter-butyl alcohol

Explanation: Lucas test is used to distinguish between alcohols. Tertiary alcohols react the fastest, followed by the secondary alcohols and the…

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Correct answer: 1 - Pentanol

346. Alcohol is less acidic than phenol due to:

  • A. higher ka value
  • B. stability of carbocation
  • C. Instability of alkoxide ion
  • D. Stability of phenol

Explanation: The more unstable an alkoxide will be the less acidic it will be. An alkoxide is less stable than a phenoxide causing it to have a less…

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Correct answer: Instability of alkoxide ion

347. The dehydration of ethyl alcohol with concentrated H2SO4 at 140°C gives:

  • A. Ethene (ethylene)
  • B. Diethyl ether
  • C. Alcohol
  • D. Carboxylic acid

Explanation: When ethanol is heated with conc. H2SO4 at140∘C (413K), the product obtained is diethyl ether.

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Correct answer: Diethyl ether

348. Which will not react with phenol:

  • A. NaOH
  • B. KMnO4/OH-
  • C. Br2
  • D. Na

Explanation: Potassium permanganate (KMnO4)/OH- will oxidise phenol to form 1,4-dihydroxybenzene, also known as hydroquinone.

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Correct answer: KMnO4/OH-

349. The order of reactivity of alcohols when C - O bonds break:

  • A. Tertiary > Primary
  • B. Tertiary < Secondary < Primary
  • C. Tertiary < Secondary
  • D. Tertiary = Secondary = Primary

Explanation: The correct order of reactivity of alcohols when the C-O bond breaks is tertiary > secondary > primary.

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Correct answer: Tertiary > Primary

350. The question is given below:

  • A. B will be a zero vector
  • B. B will be a non-zero vector
  • C. B and A are parallel to each other
  • D. A and B are perpendicular to each other

Explanation: The following is the solution: Given that a.b = 0 Then, either |a| = 0 or |b| = 0 or a⊥b (in case a and b are non-zero) and if a×b=0 then…

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Correct answer: B will be a zero vector

351. Which one of the following alcohol is indicated by formation of yellow crystals in Iodoform test?

  • A. Methanol
  • B. Ethanol
  • C. Butanol
  • D. Propanol

Explanation: Only secondary alcohols with a methyl group on the carbon atom adjacent to the hydroxyl group give a positive iodoform test.

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Correct answer: Ethanol

352. Oxidation of alcohols convert them into:

  • A. Aldehydes
  • B. Acids
  • C. Alkanes
  • D. Ethers

Explanation: The oxidation of alcohols can convert them into aldehydes, ketones, carboxylic acids, and even alkenes.

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Correct answer: Aldehydes

353. The best resgent for the oxidation of alcohols is:

  • A. ZnCl2
  • B. Acid dichromate
  • C. Ether
  • D. Pyridine

Explanation: The best reagent for oxidizing primary alcohols to carboxylic acids is strong oxidizing agents such as K2Cr2O7 (potassium dichromate).

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Correct answer: Acid dichromate

354. Among the following alkenes, which one produces a tertiary butyl alcohol on acid-catalyzed hydration?

  • A. 2-Butene
  • B. 1-Butene
  • C. 2-Methylpropene
  • D. 1-Pentene

Explanation: Acid-catalyzed hydration of an alkene follows Markovnikov's rule, proceeding through the most stable carbocation intermediate.

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Correct answer: 2-Methylpropene

355. Identify a tertiary alcohol:

  • A. 2-pentanol
  • B. 2 - Methyl - 2 - butanol
  • C. 2,2-Dimethyl - 1 propanol
  • D. 3 - Methyl - 2 -butanol

Explanation: A tertiary alcohol is one where the hydroxyl (-OH) group is attached to a carbon atom that is bonded to three other carbon atoms.

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Correct answer: 2 - Methyl - 2 - butanol

356. Which of the following reacts with aqueous alkaline iodine togive a yellow precipitate?

  • A. 1-Propanol
  • B. Ethanol
  • C. Methanol
  • D. 2-Methyl-2-propanol

Explanation: This describes the iodoform test. The test is positive for compounds containing a methyl ketone group (CH₃-CO-) or alcohols that can be…

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Correct answer: Ethanol

357. In this section of logical deduction, the question consists of a brief passage (usually a report containing certain data regarding some social or economic problem), followed by certain inferences based on it. The student is required to analyze the contents (or data) of the passage and grasp the desirable facts from it. Then, student has to consider each of the given inferences in the context of the given passage. decide upon its degree of truth or falsity and then choose the hest alternative provided accordingly.In the overall economy of Pakistan, agriculture is the largest sector of economic activity. It plays a crucial role in the country's economic development by providing food to its people and raw materials to industry. It accounts for the largest share to the national income. The share of the various agricultural commodities, animal husbandry and ancillary activities has been more than 40 percent since independence. During the decade of the fifties, it actually contributed about half of the national output.Agriculture contributes to national income more than all other activities put together.

  • A. Definitely true
  • B. Probably true
  • C. Data inadequate
  • D. Probably false
  • E. Definitely false

Explanation: The correct answer is 'Probably true' because the passage clearly states that agriculture is the largest sector of economic activity in…

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Correct answer: Probably true

358. Directions: In the following question, a number sequence is given with one term missing. Choose the correct term that will continue the same pattern and replace the question mark in the given sequence.2,7,5,5,8,3,11,?

  • A. 1
  • B. 0
  • C. 2
  • D. 3

Explanation: The sequence 2, 7, 5, 5, 8, 3, 11, ? can be broken into two interleaved subsequences: Odd-position terms: 2, 5, 8, 11 - This subsequence…

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Correct answer: 1

359. In the following question, two statements numbered I and II are given. There may be cause and effect relationship between the two statements. These two statements may be the effect of the same cause or independent causes. These statements may be independent causes without saving any relationship. Read both the statements in question and mark your answer as:A. If statement I is the cause and statement II is its effect;B. If statement II is the cause and statement, I is its effect;C. If both the statements I and II are independent causes;D. If both the statements I and II are effects of independent causes;E. If both the statements I and II are effects of some common causes;I. The Punjab university has instructed all the colleges under its jurisdiction to ban smoking inside the college premises as well as in the hostels.II. Majority of the parents signed a joint petition and are complaining against the open environment for students in colleges.

  • A. A. If statement I is the cause and statement II is its effect;
  • B. B. If statement II is the cause and statement I is its effect;
  • C. C. If both the statements I and II are independent causes;
  • D. D. If both the statements I and II are effects of independent causes;
  • E. E. If both the statements I and II are effects of some common cause;

Explanation: Statement II is the cause because the majority of parents were concerned about the open environment in colleges, leading them to sign a…

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Correct answer: B. If statement II is the cause and statement I is its effect;

360. In this question, a statement is given followed by two courses of action numbered I and II. It is required to grasp the statement, analyze the problem or policy it mentions and then decide which of the courses of action logically follow / most appropriate.Statement:Most of the students who study in premier engineering colleges in Pakistan migrate to developed nations for better prospects in their professional pursuits.Courses of action:I) All the students joining these colleges should be asked to sign a bond at the time of admission that they will remain in Pakistan at least for twenty years after they complete education.II) All those students should be asked to pay the entire cost of their education which the government subsidizes who desire to settle in the developed nations.

  • A. If only I follow
  • B. If only II follows
  • C. If either I or II follows
  • D. If neither I nor II follows
  • E. If both I and II follows

Explanation: The correct answer is Option B: If only II follows. The statement highlights the issue of students from premier engineering colleges in…

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Correct answer: If only II follows
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