Terylene is a polymer of which components?

Among the following,the correct statement$(s)$ about polymers is(are):
$A$. The polymerization of chloroprene gives natural rubber.
$B$. Teflon is prepared from tetrafluoroethene by heating it with persulphate catalyst at high pressures.
$C$. $PVC$ are thermoplastic polymers.
$D$. Ethene at $350-570 \ K$ temperature and $1000-2000 \ atm$ pressure in the presence of a peroxide initiator yields high density polythene.

Formaldehyde is not present as a monomer in:

Low density polythene and high density polythene,both are polymers of ethene but there is marked difference in their properties. Explain.

Which of the following is a biodegradable polymer of polyamide class?

The synthetic rubber neoprene is a .....