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:

Bakelites are

Acetate rayon is prepared from

Phenol and formaldehyde undergo condensation to give a polymer $(A)$ which on heating with formaldehyde gives a thermosetting polymer $(B)$. Name the polymers. Write the reactions involved in the formation of $(A)$. What is the structural difference between the two polymers?

Which of the following statements is incorrect?

Rayon fibers are obtained from .......