When benzene sulfonic acid and p-nitrophenol are treated with $\mathrm{NaHCO}_{3}$, the gases released respectively are

(D) $\mathrm{CO}_{2}, \mathrm{CO}_{2}$

(A) $\mathrm{SO}_{2}, \mathrm{NO}_{2}$

(B) $\mathrm{SO}_{2}, \mathrm{NO}$

(C) $\mathrm{SO}_{2}, \mathrm{CO}_{2}$

JEE Advanced · 2006 · 09 Apr 2006 · Alcohols Phenols and Ethers

When benzene sulfonic acid and p-nitrophenol are treated with

NaHCO_{3}

, the gases released respectively are

Answer: (D)

Both benzene sulfonic acid and p-nitrophenol are acidic enough to react with

NaHCO_{3}

(a weak base) to release

CO_{2}

gas. Benzene sulfonic acid is a strong acid (

pK_{a} \approx - 2.5

), and p-nitrophenol is a weak acid (

pK_{a} \approx 7.2

) but still acidic enough due to the electron-withdrawing nitro group. Both react:

HA + NaHCO_{3} \to NaA + H_{2} O + CO_{2} ↑

JEE Advanced · 2006 · 09 Apr 2006 · Single correct option