Question

Assertion: $p$-Nitro phenol is a stronger acid than $o$-nitro phenol.

Reason: Intramolecular hydrogen bonding makes ortho-isomer weaker acid than para-isomer.

• A. Both Assertion and Reason are false.
• B. Assertion is true, but Reason is false.
• C. Both Assertion and Reason are true. The reason is the correct explanation of Assertion.
• D. Both Assertion and Reason are true. The reason is not the correct explanation of Assertion.

Answer 1

The correct option is C

Both Assertion and Reason are true. The reason is the correct explanation of Assertion.

The explanation for the Assertion statement

• The hydroxyl group $(-\mathrm{OH})$ and nitrogen are in close proximity in $o$-nitro phenol; the hydrogen atoms attached to the oxygen establish a hydrogen bond.
• It forms intramolecular hydrogen bonding.
• Since and in the hydroxyl group of $p$-nitro phenol are relatively far apart, intramolecular hydrogen bonding cannot be formed between the hydrogen attached to the oxygen in the hydroxyl group.
• Due to intramolecular hydrogen bonding, $p$-nitrophenol is a stronger acid than $o$-nitrophenol.

The explanation for the Reason statement

• Hydrogen bonding is the term for the electrostatic attraction between hydrogen and the second row's most electronegative elements.
• There are two types of hydrogen bonding: intra- and intermolecular.
• The $o$-isomer is weaker acid than $p$-isomer due to intramolecular hydrogen bonding.
• As a result, $p$-nitrophenol is more acidic than $o$-nitrophenol as H atom is free for donation in $p$-nitrophenol.

Therefore, the correct option is (C) Both Assertion and Reason are true. The reason is the correct explanation of Assertion.