Explain why the benzene molecule usually reacts with electrophiles

Explanation:Because of the delocalised electrons exposed above and below the plane of the rest of the molecule, benzene is obviously going to be highly attractive to electrophiles - species which seek after electron rich areas in other molecules.

Benzene has a pi electron system that is electron rich.

Electrophiles are molecules that are attracted to electron rich molecules as they are electron deficient in order to form a more stable complex.

Hence, as benzene is electron rich, electrophiles will be attracted to it.