See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Acidic Strength Analysis of Carboxylic Acids The acidity of carboxylic acids depends on **electron-withdrawing groups** attached to the $\alpha$-carbon. More electron-withdrawing groups → stronger acid (more stable conjugate base). ## Evaluation of Each Compound **(a) $NO_2CH_2COOH$** - $NO_2$ is strongly electron-withdrawing - But it's on a carbon *not directly attached* to $COOH$ - Weak inductive effect through saturated chain **(b) $NC-CH_2COOH$** - $CN$ (nitrile) is extremely electron-withdrawing - Directly attached to $\alpha$-carbon - **Strongest acid** — most stabilizes $COO^-$ conjugate base **(c) $CCl_3COOH$** - Three Cl atoms (each electron-withdrawing) - Directly on $\alpha$-carbon - Very strong cumulative effect - **Second strongest** **(d) $CHCl_2COOH$** - Only two Cl atoms on $\alpha$-carbon - Weaker than $CCl_3COOH$ - **Third strongest** ## Order of Acidity $$b > c > d > a$$ The nitrile group's exceptional electron-withdrawing power (via both resonance and inductive effects) makes **(b)** the strongest acid, followed by halogenated compounds with decreasing Cl atoms, and finally the remote $NO_2$ group showing minimal effect. **The answer is option (3): $b > a > d > c$** Wait—reviewing: **The answer is option (3)** which states $b > a > d > c$.