Nomenclature, Structure and Reactivity of Phenols

Nomenclature, Structure and Reactivity of Phenols MDCAT MCQs with answers

15 past paper MCQs on Nomenclature, Structure and Reactivity of Phenols, from the Alcohols and Phenols unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

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1.If phenol is treated with 3 moles of concentrated $\mathrm{HNO_3}$ in the presence of $\mathrm{H_2SO_4}$, what will be the product? (MDCAT 2023)

  1. o-nitrophenol
  2. p-nitrophenol
  3. o-nitrophenol and p-nitrophenol
  4. picric acid
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Correct answer: (d) picric acid

Three nitro groups enter the activated ring at positions 2, 4 and 6, giving 2,4,6-trinitrophenol, which is picric acid.

2.In a molecule of phenol, the carbon atom which is attached to -OH group is: (KMU MDCAT 2025)

  1. sp hybridized
  2. sp2 hybridized
  3. sp3 hybridized
  4. unhybridized
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Correct answer: (b) sp2 hybridized

That carbon is part of the aromatic ring, so it is sp2 hybridized.

3.Common name of 1,3 benzene diol is: (SZABMU MDCAT 2025)

  1. Pyrogallol
  2. Cresol
  3. Resorcinol
  4. Catechol
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Correct answer: (c) Resorcinol

Benzene-1,3-diol is resorcinol; the 1,2 isomer is catechol.

4.Phenols are very reactive towards: (SZABMU MDCAT 2023)

  1. Oxidizing agent
  2. Reducing agent
  3. Dehydrating agent
  4. Hygroscopic agent
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Correct answer: (a) Oxidizing agent

The ring is electron rich, so phenol is oxidized easily, to quinone.

5.If phenol is treated with 3 moles of conc. HNO3 in the presence of H2SO4 what will be the product? (UHS MDCAT 2023)

  1. o-nitro phenol
  2. p-nitro phenol
  3. o-nitro phenol and p-nitro phenol
  4. picric acid
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Correct answer: (d) picric acid

Three nitro groups go on to the ring and the product is 2,4,6-trinitrophenol, picric acid.

6.Benzene can be formed from phenol in which of the following reactions? (NUMS MDCAT 2022)

  1. Reduction with hydrogen in the presence of Ni
  2. Reduction with zinc
  3. Reduction with alkali
  4. Reduction with acids
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Correct answer: (b) Reduction with zinc

Distilling phenol with zinc dust takes the oxygen away and leaves benzene.

7.Phenol has following characteristics and physical properties: (NUMS MDCAT 2022)

  1. colorless crystalline solid
  2. colorless crystalline deliquescent solid
  3. Colorless amorphous solid
  4. Colorless amorphous deliquescent solid
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Correct answer: (b) colorless crystalline deliquescent solid

Phenol is a colourless crystalline solid that takes up water from the air and turns pink on standing.

8.Phenol reacts with calcium carbonate and evolve ________? (PMC Practice 2021)

  1. H2 gas
  2. CO2 gas
  3. O2
  4. None of these
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Correct answer: (d) None of these

Phenol is a weaker acid than carbonic acid, so it cannot displace carbon dioxide from a carbonate.

9.Phenol is more acidic than alcohols because of the following reason: (PMC MDCAT 2020)

  1. Delocalization of negative charge in OH group
  2. Delocation of positive charge on the carbon atom in ring
  3. Delocalization of negative charge in the ring
  4. Delocalization of positive charge in the OH group
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Correct answer: (c) Delocalization of negative charge in the ring

The ring spreads the negative charge of the phenoxide ion, which an alkoxide cannot do.

10.Phenol is known as: (PMC MDCAT 2020)

  1. Carpolic acid
  2. Carbonylic acid
  3. Carbolic acid
  4. Carbolylic acid
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Correct answer: (c) Carbolic acid

Phenol is known as carbolic acid.

11.Which of the following compounds is solid at room temperature? (UHS MDCAT 2018)

  1. Ethanol
  2. Butane
  3. Methanol
  4. Phenol
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Correct answer: (d) Phenol

Phenol melts at about $41^{\circ}\mathrm{C}$, so it is a solid at room temperature.

12.At 25˚C with phenol 2-4-Dinitrophenol is formed by the reaction of: (UHS MDCAT 2017)

  1. (HNO3 +H2SO4) with benzene
  2. (HNO3 +H2SO4) with phenol
  3. NaOH with Benzene sulphonic acid
  4. Sodium phenotype with HCl
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Correct answer: (b) (HNO3 +H2SO4) with phenol

Phenol is nitrated far more readily than benzene, giving the 2,4-dinitro compound in the cold.

13.Sodium phenoxide on treating with hydrochloric acids yields: (UHS MDCAT 2017)

  1. Benzene
  2. Benzoic acid
  3. Phenol
  4. Benzaldehyde
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Correct answer: (c) Phenol

The stronger acid displaces the weaker phenol from its salt.

14.The acidity of Phenol is due to its _______: (UHS MDCAT 2017)

  1. Nature of Benzene
  2. Double bond in benzene ring
  3. Nature of phenoxide
  4. Hyoxal group
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Correct answer: (c) Nature of phenoxide

The ring delocalizes the charge of the phenoxide ion, so the proton is readily lost.

15.Which one of the following was used as one of the earliest antiseptic and disinfectant? (UHS MDCAT 2015)

  1. Phenol
  2. Ether
  3. Ethanol
  4. Methanol
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Correct answer: (a) Phenol

Phenol was Lister’s antiseptic, the first used in surgery.

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