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JEE Main 202431 JanuaryMorning Shift
Exam
JEE Main
Year
2024
Date
31 January
Shift
Morning Shift
Subject
Chemistry
Chapter
Alcohols Phenols and Ethers

JEE Main 2024 · 31 January · Morning Shift · Chemistry · Alcohols Phenols and Ethers

Given below are two statements: One is labelled as Assertion A and...

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R:

Assertion A: pKap{K}_{a} value of phenol is 10.010 . 0 while that of ethanol is 15.915 . 9.

Reason R: Ethanol is stronger acid than phenol.

In the light of the above statements, choose the correct answer from the options given below:

Options

  1. AA is true but R is false
  2. BA is false but R is true
  3. CBoth A and R are true and R is the correct explanation of A
  4. DBoth A and R are true but R is NOT the correct explanation of A.

Correct answer

A. A is true but R is false

Step-by-step solution

pKa{pK}_{a} is a measure of the acidity of a particular molecule. It measures the strength of an acid by how tightly a proton is held by a Bronsted acid. The lower the value of pKa{pK}_{a}, the stronger the acid and the greater its ability to donate its protons. describe the acidity of a particular molecule.

pKa=−logKa{pK}_{a} = - {logK}_{a}

Hence, Assertion is true,

Phenol is more acidic than ethanol because after losing a proton (H+)\left({H}^{+}\right), phenol forms phenoxide ion which is stabilised by resonance whereas ethoxide ion is not.

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