Which of the following compounds is used for the production of $Nylon-6,6$?

The species which can best serve as an initiator for the cationic polymerization is:

The monomers used in the production of $Nylon-66$ are ........

Which of the following is the common monomer for the polymers Bakelite and Melamine?

When the condensation product of hexamethylenediamine and adipic acid is heated to $553 \ K \ (280^\circ C)$ in an atmosphere of nitrogen for about $4-5$ hours,the product obtained is

The initiator used in cationic polymerization is........