Amines Part 3

Concept:Electron-donating groups (EDG) increase the stability of diazonium salts by dispersing the positive charge. Electron-withdrawing groups (EWG) decrease stability.Explanation:The diazonium ion $\mathrm{ArN}_2^+$ is stabilised by EDG that push electrons towards the ring, reducing the positive charge density.$- \mathrm{OCH}_3$ is a strong EDG; $- \mathrm{CH}_3$ is a weak EDG.$- \mathrm{Cl}$ is a weak EWG (inductive withdrawal dominates over +M effect for diazonium stability).$- \mathrm{NO}_2$ is a strong EWG.Thus stability order: $- \mathrm{OCH}_3 > - \mathrm{CH}_3 > - \mathrm{Cl} > - \mathrm{NO}_2$.In the given compounds: A = para-$\mathrm{OCH}_3$, B = para-$\mathrm{NO}_2$, C = para-$\mathrm{CH}_3$, D = para-$\mathrm{Cl}$.So the correct order is A > C > D > B.Answer:Option B: $A \gt C \gt D \gt B$