Final answer:
Strong deactivating groups typically carry a negative charge, due to their electron-withdrawing nature and the presence of electronegative atoms that stabilize the charge through delocalization.
Step-by-step explanation:
Strong deactivating groups usually have a negative charge. This is because such groups are typically electron-withdrawing, pulling electron density away from the reaction center, which can deactivate the molecule towards further substitution reactions. This electron-withdrawing capability is often facilitated by inductive effects or the presence of one or more electronegative atoms within the group, which stabilize the negative charge through charge delocalization. Deactivating groups such as nitro (-NO2) or cyano (-CN) are common examples where their strong electronegative nature and ability to delocalize electrons make them strong deactivating groups in organic chemistry.