Question

p-Nitrophenol is a stronger acid than phenol while p-cresol is a weaker acid. This can be explained as:

• A. $-C{H}_3$ group decreases the electron density on the oxygen of $O-H$ group making p-cresol a weaker acid
• B. $-N{O}_2$ group decreases electron density on the oxygen of $O-H$ group making p-nitrophenol a stronger acid
• C. $-C{H}_3$ group increases the electron density on the oxygen of $O-H$ group making the release of $H^{+}$ easier
• D. $-N{O}_2$ group increases the electron density on oxygen of O-H group making release of $H^{+}$ easier.

Answer 1

The correct option is B $-N{O}_2$ group decreases electron density on the oxygen of $O-H$ group making p-nitrophenol a stronger acid

$-N{O}_2$ group being electron withdrawing group, decreases electron density on oxygen $O-H$ group thus making the release of $H^{+}$ easier hence increasing the acidity of phenol. $-C{H}_3$ group increases the electron density on oxygen atom thus decreasing acidity than phenol.