JEE Main · 2021 · Shift-ImediumBOND-165

Given below are two statements: Statement I: o-Nitrophenol is steam volatile due to intramolecular hydrogen bonding.…

Chemical Bonding · Class 11 · JEE Main Previous Year Question

Question

Given below are two statements:

Statement I: o-Nitrophenol is steam volatile due to intramolecular hydrogen bonding.

Statement II: o-Nitrophenol has high melting point due to hydrogen bonding.

Choose the most appropriate answer:

Options
  1. a

    Both Statement I and Statement II are false

  2. b

    Statement I is true but Statement II is false

  3. c

    Statement I is false but Statement II is true

  4. d

    Both Statement I and Statement II are true

Correct Answerb

Statement I is true but Statement II is false

Detailed Solution

🧠 Compare o-nitrophenol and p-nitrophenol: the ortho isomer forms intramolecular H-bonds (the –OH and adjacent –NO₂ form a ring within the molecule).

🗺️ Evaluate Statement I — o-Nitrophenol is steam volatile due to intramolecular H-bonding:

The intramolecular H-bond in o-nitrophenol "locks up" the –OH group → the O–H cannot interact with water molecules → less association with water → volatilized with steam (steam-distillable). ✓

Statement I is TRUE

Evaluate Statement II — o-Nitrophenol has HIGH melting point due to H-bonding:

Because the –OH in o-nitrophenol forms an intramolecular H-bond, there are fewer intermolecular H-bonds available → lower intermolecular association → lower melting point compared to p-nitrophenol (which has extensive intermolecular H-bonding and is NOT steam-volatile).

Statement II is FALSE

⚡ Intramolecular H-bonding REDUCES intermolecular associations → lowers melting point and boiling point and increases volatility.

Answer: Statement I is true but Statement II is false\boxed{\text{Answer: Statement I is true but Statement II is false}}

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Given below are two statements: Statement I: o-Nitrophenol is steam volatile due to intramolecular… (JEE Main 2021) | Canvas Classes