Answer
a. p-amino aniline and terephthalic acid are used to make kevlar which is written below.
b. Structure of the Nomex Polymer is written below.
In Kevlar, -CONH groups are present at para position whereas in Nomex -CONH groups are present at meta position of the benzene ring.
Work Step by Step
a) To write the monomers of Kevlar, we have to look at the structure of Kevlar. The dimer is formed by elimination of water molecule. So, -CONH i.e. peptide bond is formed. So, in one monomer, there are two $-NH_{2}$ groups are at para position of the benzene ring and in another monomer , there are two -COOH groups are at para position of the benzene ring. That's how we get the monomers of Kevlar.
b) Condensation reaction occurs here where one H is eliminated from one $NH_{2}$ group and one OH is eliminated from one $COOH$ group and we get the polymer.
