Consider the following substituted benzenediazonium salts: (A) p-Nitrobenzenediazonium (B) p-Methylbenzenediazonium (C) p-Methoxybenzenediazonium (D) Benzenediazonium The correct decreasing order of their reactivity as electrophiles in an azo coupling reaction with phenol is:

Step-by-step solution

In an azo coupling reaction, the diazonium ion acts as an electrophile. The reactivity of the electrophile increases as the magnitude of the positive charge on the diazonium nitrogen increases. Electron-withdrawing groups increase the positive charge on nitrogen, making the diazonium ion a stronger electrophile (more reactive). Conversely, electron-donating groups disperse the positive charge, making it a weaker electrophile (less reactive). Analyzing the substituents: (A) -NO2 is a strong electron-withdrawing grou