See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Acidity Order of Phenolic Compounds **Step 1: Identify the compounds** - (I) Phenol (unsubstituted) - (II) p-Cresol (para-methyl phenol) - (III) m-Nitrophenol (meta-nitro phenol) - (IV) p-Nitrophenol (para-nitro phenol) **Step 2: Apply electronic effects on phenolic acidity** Phenol acidity increases when electron-withdrawing groups stabilize the phenoxide anion ($\ce{PhO^-}$) through resonance and inductive effects. Electron-donating groups decrease acidity. **Step 3: Evaluate each compound** - **(I) Phenol**: Reference compound, moderate acidity - **(II) p-Cresol**: $\ce{CH3}$ is electron-donating (activating) → decreases acidity (least acidic) - **(III) m-Nitrophenol**: $\ce{NO2}$ (meta position) is electron-withdrawing but meta-position doesn't allow direct resonance stabilization → moderate increase in acidity - **(IV) p-Nitrophenol**: $\ce{NO2}$ (para position) is strongly electron-withdrawing AND ortho/para directing, allowing direct resonance stabilization of the negative charge → most acidic **Step 4: Order by acidity** $$\ce{IV > III > I > II}$$ or equivalently: **p-Nitrophenol > m-Nitrophenol > Phenol > p-Cresol** **Answer: (B) I > IV > III > II** ✓ This correctly ranks the relative acidity of the four compounds.