See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: Acidity Order of Benzoic Acid Derivatives **Key Principle:** Electron-withdrawing groups increase acidity; electron-donating groups decrease acidity. **Analysis of substituents:** - **$OCH_3$ (para):** Electron-donating group → decreases acidity (least acidic) - **$H$ (unsubstituted benzoic acid):** Reference compound → moderate acidity - **$NO_2$ (para):** Electron-withdrawing group → increases acidity (most acidic) **Reasoning:** The $NO_2$ group is strongly electron-withdrawing through both inductive and resonance effects. It stabilizes the conjugate base ($COO^-$) by delocalizing negative charge through the aromatic ring. The $OCH_3$ group is electron-donating (activating), which destabilizes the conjugate base and makes the acid weaker. **Correct order (increasing acidity):** $$p\text{-}OCH_3\text{-benzoic acid} \,<\, \text{benzoic acid} \,<\, p\text{-}NO_2\text{-benzoic acid}$$ **Option (1) is correct** because it properly arranges: - Weakest acid (with $OCH_3$) on the left - Strongest acid (with $NO_2$) on the right - Unsubstituted in the middle