Which polymer is used in the manufacture of contact lenses for the eyes?

Which of the following is an example of a fibre?

The polymer used for optical lenses is

The number average molecular mass $(M_n)$ and weight average molecular mass $(M_w)$ of a polymer are $30000$ and $40000$ respectively. The polydispersity index $(PDI)$ of the polymer is:

Explain the difference between Buna $-N$ and Buna $-S$.

The monomer units of nylon-$6, 6$ and nylon-$2$-nylon-$6$ are respectively: