During the acetylation of amines,what is replaced by acetyl groups?

Account for the following:
$(i)$ $pK_{b}$ of aniline is more than that of methylamine.
$(ii)$ Ethylamine is soluble in water whereas aniline is not.
$(iii)$ Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.
$(iv)$ Although amino group is $o-$ and $p-$ directing in aromatic electrophilic substitution reactions,aniline on nitration gives a substantial amount of $m$-nitroaniline.
$(v)$ Aniline does not undergo Friedel-Crafts reaction.
$(vi)$ Diazonium salts of aromatic amines are more stable than those of aliphatic amines.
$(vii)$ Gabriel phthalimide synthesis is preferred for synthesising primary amines.

The increasing order of nucleophilicity of the following nucleophiles is: $a. CH_3CO_2^-$,$b. H_2O$,$c. CH_3SO_3^-$,$d. OH^-$

What is the major product of the following reaction?
$C_6H_5NO_2 \xrightarrow{Zn / NH_4Cl} \text{Product}$

Identify $A$ in the following reaction.

The correct order of basic strength for the given compounds is: