Identify the monomers in the following polymeric structures:
$(i)$ $-[CO-(CH_2)_8-CO-NH-(CH_2)_6-NH]-_n$
$(ii)$ Melamine-formaldehyde polymer

(N/A) $(i)$ The monomers of the given polymeric structure (Nylon-$6,6$) are decanedioic acid $[HOOC-(CH_2)_8-COOH]$ and hexamethylene diamine $[H_2N-(CH_2)_6-NH_2]$.
$(ii)$ The monomers of the melamine-formaldehyde polymer are melamine $(C_3H_6N_6)$ and formaldehyde $(HCHO)$.