Question

The correct order of acid character of the following compounds is :

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• A. $IV>III>II>I$
• B. $I>II>III>IV$
• C. $III>II>I>IV$
• D. $II>III>IV>I$

Answer 1

The correct option is D $II>III>IV>I$

Acidic strength


carboxylic acids are more acidic than phenols.
Reason:
The negative charge in carboxylate ion is dispersed over two oxygen atoms whereas in phenoxide it is distributed over only one oxygen atom.
Hence, the carboxylate ion is more stable than the phenoxide ion. Hence, carboxylic acids are more acidic than phenol and alcohol because of greater resonance stabilization of their conjugate base.
$I$ is the least acidic

$-I$ and $-R$ effect increase the acidic strength since electron-withdrawing group will increase the acidity by stabilize the negative charge formed after the loss of $H^{+}$, whereas $+I$and $+R$ effect decrease the acidic strength of carboxylic acids.
Correct order is
$II>III>IV>I$