Giving justification, categorise the following moelcules/ions as nucleophile or electrophile:
`HS^(-),BF_(3),C_(2)H_(5)O^(-),(CH_(3))_(3)N`:
`Coverset(+)(l),CH_(3)-overset(+)(C)=O,H_(2)Nbar:,overset(+)(N)O_(2)`

Explanation

Nucleophiles: `HS^(-),C_(2)H_(5)O^(-),(CH_(3))_(3)N:,H_(2)N:^(-)`
These species have unshared pair of electrons, which can be donated and shared with an electrophile.
Electrophiles : `BF_(3),Coverset(+)l,CH_(3)-overset(+)(C)=O,overset(+)(N)O_(2)`.
Reactive sites have only six valence electrons, can accept electron pair from a nucleophile.