(a) Acetylation of aniline results in a decrease of electron density on nitrogen so, its activation effect reduces.
(b) In case of aniline the lone pair of −NH2 is in conjugation with the benzene ring due to which the electron density is less available on the N-atom. Hence, the electron density on nitrogen atom is higher which leads to higher basicity.
(c) Aromatic amine is highly reactive and it reacts with acidic hydrogen of nitrating agent and from anilinium ion whichgives meta product.