Question

Choose the correct statement regarding the given compounds :

• A. $I$ is more acidic than $II$
• B. $I$ is less acidic than $II$
• C. $III$ is less acidic than $IV$
• D. $III$ is more acidic than $IV$

Answer 1

Answer: (B), (C)

The correct options are
B $I$ is less acidic than $II$
C $III$ is less acidic than $IV$

$\text{Stability of conjugate base}\propto \text{Acidic strength}$
For I and II :
Conjugate base formed :



As seen, $-C{H}_3$ group shows $+I$ effect and thus destabilizes the negative charge by increasing the electron density. Thus, the stability of conjugate base formed by structure I is less as compared to conjugate base formed by II.
So, I is less acidic than II.

Similarly for III and IV:



$-C{H}_3$ group shows $+I$ effect and thus destabilizes the negative charge by increasing the electron density. Thus, the stability of conjugate base formed by structure III is less as compared to conjugate base formed by IV.
So, III is less acidic than IV.