Which of the following is $NOT$ correct for Terylene?

Which of the following has been used in the manufacture of non-inflammable photographic films?

$Celanese$ silk is

Which one of the following is used in the preparation of cellulose nitrate?

Identify the correct structure of caprolactam :-

If the number average molecular weight and weight average molecular weight of a polymer are $40000$ and $60000$ respectively, the polydispersity index of the polymer will be