Nylon thread is made of........

Which of the following is $NOT$ true about natural rubber?

Natural rubber is a polymer of ....

Which of the following statements is incorrect about $Novolac$?

Which of the following statements are correct?
$a$. Natural rubber becomes soft and sticky at high temperature.
$b$. Neoprene is a polymer of $2-$chloro$-1,3-$butadiene.
$c$. Nylon $6,6$ is a polyamide fibre.
$d$. Buna$-S$ is an example of a homopolymer.

Intermolecular forces in nylon-$6,6$ are