Identify the correct order of acidic strength for the following compounds: (i) (ii) (iii)

Step-by-step solution

The acidic strength of unsaturated carboxylic acids is determined by the stability of their conjugate base (carboxylate anion). Electron-withdrawing groups stabilize the carboxylate anion via the -I effect, increasing acidity. Electron-donating groups destabilize the anion via the +I effect, decreasing acidity. In compound (ii), the - Cl atom exerts a strong -I effect. Being cis to the - COOH group, it effectively stabilizes the conjugate base, making compound (ii) the most acidic. Compound (iii) has one - CH ₃ gro