Benzene diazonium salts are highly stable compounds due to the phenomenon of resonance. Resonance is a chemical phenomenon that occurs when electrons are delocalized or spread out over multiple atoms or bonds. In the case of benzene diazonium salts, resonance plays a crucial role in stabilizing the compound.

Resonance in benzene diazonium salts:
1. Structure of benzene diazonium salts:
- Benzene diazonium salts have a diazonium group (-N2+) attached to a benzene ring.
- The diazonium group consists of a nitrogen atom bonded to two oxygen atoms, one of which is positively charged.

2. Resonance structures:
- The positive charge on the diazonium group can be delocalized or spread out over the benzene ring through resonance.
- Resonance structures can be drawn by moving the positive charge around the benzene ring, with the double bonds shifting accordingly.
- The resonance structures show that the positive charge is not localized on a specific carbon atom in the benzene ring but rather spreads out over multiple carbon atoms.

3. Stability due to resonance:
- The delocalization of the positive charge over the benzene ring increases the stability of the compound.
- This is because the spreading out of the charge reduces the electron density at any one carbon atom, making it less susceptible to attack or reaction.
- The stability provided by resonance makes benzene diazonium salts less reactive and more resistant to decomposition.

In conclusion, the stability of benzene diazonium salts is primarily due to resonance. The delocalization of the positive charge over the benzene ring through resonance increases the stability of the compound by spreading out the charge and reducing the electron density at any one carbon atom. This stability makes benzene diazonium salts less reactive and more resistant to decomposition.