The process of heating rubber with sulfur is known as ...........

The synthetic rubber neoprene is a .....

Which of the following statements are correct?
$(1)$ Biodegradable polymers can be converted into essential life substances after degradation.
$(2)$ Non-biodegradable polymers are active towards environmental processes.
$(3)$ Non-biodegradable polymers can be converted into essential life substances.
$(4)$ $PHBV$ is degraded by bacteria under environmental conditions.

Nylon-$6,6$ is a condensation polymer of two monomers $X$ and $Y$. The number of $-CH_2-$ groups in $X$ and $Y$ are respectively

Terylene is the polyester of

Which of the following is not a polyester polymer?